A – C
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2 LAYER
Type of waterproof fabric system where the Face Fabric is bonded to a Waterproof Membrane, no Backer. Lightweight but condensation next to skin
2-WAY STRETCH
Fabric property, allowing it to stretch along one axis (warp or weft). See Mechanical Stretch & Elasticated
2.5 LAYER
Type of waterproof fabric system where the Face fabric is bonded to a waterproof membrane with a printed 1/2 layer on the inside. Lightweight with condensation a little away from the skin.
3 LAYER
Type of waterproof fabric system where the Face fabric is bonded to a waterproof membrane and a woven fabric backer. Heavier weight but most comfortable with condensation away from the skin.
37.5® TECHNOLOGY
Natural volcanic activated carbon in, or printed on, a fabric to aid moisture transmission and temperature regulation. Used in the Kamleika fabric
4-WAY STRETCH
Fabric property, allowing it to stretch along each axis (warp & weft). See Mechanical Stretch & Elasticated
A
ACTIVE FIT
Refers to clothing designed for movement. Close fitting to allow fabrics to perform and freedom of movement.
ACTIVE INSULATION
Breathable insulation, suitable for moving quickly in. Synthetic Insulation such as the Core range tends to be better than Down for Active use as opposed to Static Warmth.
B
BACKER
Lining inside a waterproof layer, usually bonded to the membrane, though in some cheaper or heavier waterproofs, a loose ‘drop lining’. Provides a space between the skin and the membrane layer. Protects the membrane from oil, salt and dirt plus increases comfort by keeping the membrane away from the skin. Usually a woven fabric.
BAMBI
The one that descends with all the grace of a toddler on Calpol. See also Stack it Stan
BEADING
When water forms discrete droplets on the surface of a fabric and can be shaken off. Caused by the DWR. When this stops, the fabric is prone to wetting out.
BEARING
The angle, usually given in degrees, between North and an object or direction of travel. Used when navigating with a map & compass, especially during a Mountain Marathon.
BEFUDDLED
The one that says its south even when the compass says north. Usually found muttering something about ‘polar reversal’. Don’t trust their Bearing
BOG ROULETTER
The one that will take a punt and usually end up thigh-deep in muck. Identifiable by their battlecry “It’ll be reeeeet!”. In Bog We Trust.
BOG WEASEL
A runner whose superior understanding and affinity with bogs allows them pass unscathed where others are left floundering as their sanity and speed is drained.
BONDED
Two fabrics joined without stitching (using glues or heat activated methods)
BREATHABLE
Allows transfer of water vapour. Driven by a difference in humidity either side of the fabric, measured in g/m2 over 24hrs. See also Wicking & Quick Drying
BUMBAG
See WaistBelt
C-Zero
A PFC free DWR treatment. Industry-standard as of 2025
C6
Fluoropolymer applied to fabric to enhance water repellency & stain resistance. Toxic chemical that is harmful to aquatic life. A ‘harmful substitution’ to C8 that was supposed to be better for the environment. To be phased out by 2025. See also DWR Polymer & PFC.
C8
An even longer chain Fluoropolymer that was replaced by C6. See also DWR, Polymer, C-Zero & PFC
CAPACITY
How much a pack or pouch can carry, measured in litres. See Volume.
CHECKPOINT CHARLIE
The one usually found playing “Battleships” i.e. circling a CP in the hope of stumbling across it. Needs a Tour Guide. See also Navago Hero.
CHECKPOINT/CP/CONTROL
Point marked on a map that is to be found during a Mountain Marathon or Fell Race.
CIRCULAR MANUFACTURE
A zero waste (or near zero) manufacturing process, allowing products to be 100% recycled at end of life to produce a high-quality secondary product, over and over again. See also InfiniOMM.
CLAG
Low cloud or mist encountered in the mountains/hills. Makes seeing where you’re going very difficult, may require taking a Bearing.
COMFORT RATING
A hypothetical temperature value applied to sleeping bags. Comfort rating (as opposed to Lower & Extreme) is the temperature at which an average female would sleep comfortably. OMM does not use this measure for sleep systems as it is not applicable to variable real-world conditions. See TOG
CONTACT FIT
OMM’s closest clothing fit. For first layer garments & leggings. See also Active & Regular Fit & Fitted
CONTOUR/CONTOURING
To traverse a slope whilst maintaining the same altitude. Allows progress across terrain without unnecessary height gain, though can involve crossing difficult and off-camber ground.
D – H
D
DENIER
Unit of weight of a yarn equating to grams per 9,000m. The higher the number stronger the fabric.
DOWN
The insulating feathers found on geese & ducks, used in the manufacture of some insulated clothing. Though very warm for its weight, it loses almost all its insulating properties when wet, making it largely unsuitable for use in typical UK conditions, especially on The OMM. See also Synthetic Insulation.
DYNAMIC DROPTAIL
Adjustable hem system used in many OMM jackets. The elastic cord is anchored just past the hips meaning the lowered hem at the rear does not ride up when tensioned. Unique to OMM.
E
ELASTICATED
Stretch fabrics utilising Elastane or similar, to provide movement. As opposed to Mechanical Stretch. High-elastic fabrics such as Lycra tend to be less insulating, which is why OMM keep quantities to a minimum in products such as the Flash Tights.
ePE
Expanded Polyethylene is a PFC-free waterproof membrane. An alternative to ePTFE.
ePTFE
Expanded polytetrafluoroethylene is a type of Membrane.
F
FACE FABRIC
Outer layer of a waterproof fabric, protects the membrane from damage. Usually treated with a DWR to help hold moisture at the surface, allowing the membrane underneath to breathe.
FELL RUNNING/RACING
The sport/pastime of running on hills, predominantly in the North of England (Fell from the Norse Fjell, indicating the Viking dominance of the region), though now widely used elsewhere. Also referred to as Hill (especially in Scotland) or Mountain Running. Typified by running off paths or trails, using navigation or animal tracks known as trods. Usually over rough ground, bog and scree. Not to be confused with Trail Running. Undertaken competitively as Fell Racing but differs from Mountain Marathon as it typically only takes place over a single day.
FELL WIZARD
The one that knows every race route inside and out, whether they’ve actually done it before or not. Usually make good, if reluctant, Tour Guides.
FITTED
A close-fitting garment designed for active use. Most OMM clothing falls into this category. Not as close as Contact Fit, should allow for layers underneath. See also Active Fit.
FLATLOCK SEAMS
A low-bulk seam created by placing two fabrics side by side (rather than overlapping as in a standard seam), allowing for stretch and reducing rub points. The raw edges of fabric are entirely covered by the threads of the seams itself.
FLUOROPOLYMER
Hydrophobic Polymer chain used in DWR treatments to hold water away from the fibres of a fabric and in the manufacture of many Membranes. Usually using the C6 structure, now known to be harmul to aquatic life. See also C-Zero, PFC & C8
FRA KIT
The obligatory equipment required to safely compete in races organised by the Fell Runners Association. Includes (as a minimum):
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Waterproof body cover (jacket & overtrousers) with integrated hood and fully taped seams
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Hat (not a buff or similar)
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Gloves
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Whistle
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Compass
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Map of the area with race route marked on
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Emergency Food
See also Kit List, Mandatory Kit & Taped Seams
FULL WEIGHT
OMM’s quoted weight for a piece of clothing or equipment with all its possible components included. See also Leanweight
G
G/M2 24hrs
Grams per metre squared over 24hrs. The amount of water vapour able to pass through a fabric, quoted as a measure of breathability. Higher the number, more breathable the fabric. See Breathable.
H
HASSLE HUFF
The one with all the Kitt but it’s someone else’s fault when they don’t know how to use it.
HILL RUNNING
Like Fell Running but Scottish. See also Trail & Mountain Running
HYDROSTATIC HEAD
A measure of a fabric’s waterproofness. Refers to how high a column of water, measured in millimetres, a fabric can withstand before allowing water through. Higher the number, the more waterproof the fabric. See Waterproof.
I – N
I
INFINIOMM
A new project (released Winter 2023), using single polymers in the manufacture of products, allowing easier and more efficient recycling at end of life, as part of a Circular Manufacture.
J
K
KIT LIST
The obligatory equipment required to safely compete in a race, as defined by the organiser (i.e. The OMM). Usually similar to the FRA Kit List but may include race or condition-specific items such as spare warm layers or tent.
L
LAMINATED
Layers of fabric bonded, rather than sewn to create a combination of characteristics. See 2, 2.5 & 3 Layer, Face Fabric, Backer & Bonded
LEANWEIGHT
The lowest possible weight that a piece of OMM clothing or equipment can achieve when all extras are removed. See Full Weight.
LOOSE LAID
In reference to a fabric. Allows for movement. Usually in insulated fabrics which can also alternatively be Stitched Through.
M
MANDATORY KIT
See Kit List & FRA Kit.
MECHANICAL STRETCH
Fabric property giving a degree of stretch, built into the fibres. Provided by the shape of weave or fibres, rather than from elastane or similar. A coil has mechanical stretch, whereas a rubber band has elastic stretch. See Elasticated, 2 & 4-Way Stretch.
MEMBRANE
A selectively permeable barrier. In fabrics, a waterproof membrane has holes big enough to allow water vapour through but small enough to not allow water droplets in and so remain waterproof yet breathable. Usually made from ePTFE (expanded polytetrafluoroethylene). The expanded bit is what makes it breathable; by stretching the membrane, it becomes microporous and it is these pores that allow the transfer of water vapour. A membrane is usually laminated to a Face Fabric and potentially a Backer, depending if the fabric is 2, 2.5, or 3 Layer, Gore-Tex and eVENT are brands of membrane, we use our own to allow us to define the exact properties we demand from our products, including additions such as 37.5 Technology as found in the Kamleika. See C6, DWR, Reproof, Taped Seam, Waterproof, Water Resistant, Weatherproof & Windproof.
MEN’S FIT
Designed to suit a body shape broader at the shoulders and chest, with a narrower waist plus longer sleeves and body length.
MOUNTAIN MARATHONS
A format of event incorporating navigation, off-road running and self-sufficiency over a minimum of two days, as pioneered in 1968 with the first-ever mountain marathon that went on to become The OMM. Think Fell Running but with a tent, stove, sleep system and full kit list on your back plus an overnight camp to contend with. All OMM clothing and equipment design stems from the demands of this kind of event. See also Fell Running, Ultra Distance, Multi-Day Events & Mountain Running.
MOUNTAIN RUNNING
The act of moving quickly through big hills on foot. Unlike Fell or Hill Running, Mountain Running is not defined by being on or off-path/trail but instead covers all aspects of running in the hills, with or without a trail!
MULTI-DAY EVENTS
Refers to running (or similar) events that take place over more than one day and include an overnight, either supported or unsupported, such as The OMM. Also applicable to self-supported fast-packing activities. The demands of such events are unique, often sacrificing comfort for weight saving. Much of OMM kit is designed for use in such events.
N
NAVAGO HERO
The one that follows you through the Clag and then sprints off when they can see where they’re going. Identifiable by their receding shout of “Cheeeeeers!” as they shoot off to the finish line.
O – S
O
OFF ROAD
Running (or walking) away from tarmac and similar surfaces. Can include smooth trail, rough fellside and everything in between.
OFF PATH/TRAIL
Away from man-made routes, across rough ground. Sometimes following a trod or a bearing and sometimes with an idea of where you might end up. The typical terrain for competitors on The OMM, Fell Running and Mountain Marathon.
OMM, THE
See The OMM & Mountain Marathon.
P
PACK
Rucksack, VestPack or other carrier used on a run or similar.
PFC
Polyfluorocarbons are durable polymer chains used in traditional C6 & C8 water-repellant treatments or DWR. Harmful to the aquatic environment but very good at shedding water and oils. See also C-Zero, Membrane, Polymer, ePE & ePTFE
POLYMER
Any substance composed of large molecules (macromolecules), which are multiples of simpler chemical units called monomers. Often used to refer to the dominant material in a fabric, i.e. Polyester or Nylon
PRIMALOFT®
A brand of Synthetic Insulation.
PTFE
Polytetrafluoroethylene is another type of Membrane.
Q
QUICK DRYING
Fabric property that allows for rapid evaporation or shedding of excess moisture from a garment. Ideal for typical UK Conditions when likely to get wet. Essential in first layers as it reduces the chilling effect of moisture on the skin. See also Wicking.
R
RACE VEST
A type of pack that distributes the load around the wearer’s body for better access and stability. Usually comprised of a compartment on the wearer’s back plus pockets on the chest, suitable for water carriers, food and accessories. Unlike a traditional rucksack, the shoulder straps are replaced with a stretch or fitted fabric, more like a piece of clothing. See VestPack.
RAGLAN SLEEVE
A sleeve construction method that offsets the seam away from the top of the shoulders and away from potential rub points under rucksack or vest straps. The sleeve is a single piece of fabric with a diagonal seam running from the collar to the underarm which also creates a wider area under the arm which is helpful when layering.
RECCEMUNTER
The one that’s lost no matter how many recces they do.
REGULAR FIT
A looser fit, usually found in external layers and insulation. More similar to non-technical streetwear. Allows for several layers underneath.
REPROOF
The reapplication of DWR, either via a spray or washed in.
RIPSTOP
Woven fabrics reinforced with a cross hatch of stronger threads, usually nylon.
RUNNING VEST
See Race Vest & VestPack
S
SCREE
Small loose stones accumulated on a mountainside as the result of erosion. Very, very fun to run down. Not kind to waterproof trousers.
SLEEP SYSTEM
Combination of insulation pieces used for an overnight. Usually a sleeping bag or similar plus insulation from the ground such as a sleep mat. Used instead of ‘Sleeping Bag’, to allow for variances in systems used such as quilts and the Rotor Sleep Suit. See Comfort Rating & Tog.
STACK IT STAN
The one that falls over on every run. Identifiable by the large clumps of mud in their hair and grass stains on their shorts. See also Bambi.
STATIC WARMTH
Usually referred to when talking about insulation types. As opposed to Active Insulation, clothing that provides static warmth is generally less well suited to wearing during times of high output due to reduced breathability, but is usually warmer overall and better used once stopped at the overnight camp on a Multi-Day Event. See also Synthetic Insulation & Down
STITCHED THROUGH
In insulation products, a stitch running through the insulation. Helps hold the insulation in place. Less necessary for ‘wadding’ style insulation but helpful for keeping loose insulation such as down in place. See also Synthetic Insulation
SYNTHETIC INSULATION
Insulating fibres usually manufactured from polyester or plastic waste. Not as warm for its weight or pack size as down (non-synthetic) but retains most of its insulating properties when wet, making it well suited to typical UK conditions and active use, also easier to wash and dry. OMM use PrimaLoft® insulation as it is widely regarded as the best quality available; with insulating properties very close to that of down plus largely manufactured from post-consumer recycled product (PCR). Usually manufactured in a roll or sheet of ‘wadding’, think loft insulation but a lot nicer!
T – Z
T
TAPED SEAM
Seams covered with tape to prevent water ingress in waterproof clothing. Sewing two pieces of fabric together requires the making of holes for the thread, an issue when making waterproof clothing. To overcome this, it is necessary to cover the seams with waterproof tape, using a heat-activated adhesive. The presence of taped seams is often a stipulation in Kit Lists as it is an indicator of a garment being manufactured to be waterproof. All OMM Waterproofs have taped seams and are fully race compliant.
THE OMM
The Original Mountain Marathon. A 2-day journey through some of the UK’s harshest terrain, held at the end of every October since 1968, to ensure challenging weather. A test of mountain craft and resilience, ‘The OMM’ is recognised as the gold standard in Mountain challenges.
The extreme demands of the event go on to inform the design and features of OMM clothing and equipment, which in turn goes on to be used in some of the toughest events and hardest challenges the world over. Teams of two are handed a map at the startline on Day 1, marked with a series of Controls or Checkpoints, teams must find the quickest route between these points before reaching a remote overnight camp whilst carrying all the Kit List required to be self-sufficient for 36hrs, including tent, sleep system, food, fuel and clothing. They must then repeat this on Day 2 to reach the finish. See also Multi-Day Events, Ultra Distance, Fell Running & Mountain Marathon.
TOG
The tog is a measure of thermal insulance of a unit area, also known as thermal resistance. It is commonly used in the textile industry and often seen quoted for duvets and carpet underlay.
Developed at The Shirley Institute in Manchester, as an alternative to the SI unit of m2K/W.
Basic unit of Tog (insulation coefficient) is the RSI, (1m2⋅K/W). 1 tog = 0.1 RSI: Thermal resistance in togs is equal to 10x the temperature difference (in °C) between 2 surfaces of a material when the flow of heat is equal to one watt per m2. Tog is measured from the difference in temperature between a heated metal plate beneath a fabric and the air temperature above the fabric. This is a much more objective measure than Comfort Ratings, as commonly used for sleeping bags and can be applied to a wider variety of sleep systems. It is also possible to provide a Wet & Dry Tog value, useful when describing use in typical UK conditions.
TOUR GUIDE
The one with a line of NavagoHeroes following. See also Fell Wizard.
TRAIL RUNNING
Moving over manmade paths and trails, often following a predetermined route, can be done at any altitude. See also Fell & Mountain Running.
TROD
A faint path or line on the ground, often created by animals (they will usually follow the path of least resistance, i.e. contour, rather than uphill) or by occasional human foot traffic, especially on popular fell running or racing routes. Not usually marked on maps but often committed to the memories of runners and Fell Wizards. See also Trodhunter.
TRODHUNTER
The one that thinks they know all the secret lines, often found alongside a Reccemunter. Aspires to be a Fell Wizard.
TUSSOCK
Large clump of grass found in upland areas, especially moorland. Almost impossible to run on or around. Also known as Babies’ Heads.
TYPICAL UK CONDITIONS
Wet & relatively mild.
U
UGR
A horizontal daisychain of webbing across the bottom of most OMM Packs, designed to allow the attachment of various accessories.
ULTRA DISTANCE
Technically any distance covered on foot over 26.2mi (42.2km) but largely recognised to start at 31mi (50km). Also a useful shorthand for anything that involves being out in the hills for more than just a few hours.
UNISEX
Suitable fit for both typical male and female body shapes. May require sizing down for Women.
UPF
Ultraviolet Protection Factor; how much UV radiation (UVB & UVA) fabric allows to pass thorugh to the skin. i.e. UPF 30 blocks 96.7% of the UV from the sun, allowing 3.33% (1/30th) through. Differs to SPF (Sun Protection Factor) which is a measure of the time taken to redden the skin.
V
VEST PACK
A type of Race Vest with the addition of a larger capacity pack on the back, suited to Ultra Distance challenges and Mountain Marathon.