Insoles, Midsoles, Outsoles? Footwear Construction Terminology Explained

2 min readWalking

Do you know your insole from your outsole? The importance of a good lasting construction or the difference between B1, B2 or B3 rated mountain boot? If you’ve ever furrowed your brow whilst reading the product specifications of walking shoes and walking boots, then this guide to footwear construction terminology is for you.


Made from a variety of materials, the upper refers to anything above the midsole, located on the outside of your shoe or boot. The upper is most often made from leather/suede or fabric.


Sitting directly beneath your foot, the insole (often referred to as the footbed) provides abundant cushioning in key areas of your foot and also absorbs moisture away. Insoles can be taken out of your shoe, and be replaced with new ones that suit your movement.

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Sandwiched between the outsole and the upper, the midsole is one of the most important components of any boot, and one you should watch out for. A well thought out midsole can provide ample shock absorption, flex support and added cushioning.


There are a whole variety of outsole units to be considered dependant on the terrain and environment you will be wearing your footwear in. Some outsoles offer excellent traction and grip, whilst others may offer a minimal, barefoot construction for those who wish to feel the terrain beneath their feet.

For hill walking and mountain walking, a deep tread/lug is beneficial, especially in wet and muddy conditions. A widely spaced lug means less build-up of dirt, ensuring a better grip.

Vibram® is one of the world’s leading sole manufacturers, and a name you’ll come across often in outdoor footwear and is the premium choice for footwear.

Toe Counter

This stiff piece of material is placed between the lining and upper at the toe of the shoe and helps retain its shape.

Your shoe should bend at the toes, mimicking the natural movement of your foot as you push off. If the toe counter doesn’t bend, your shoe may be too ridged for nimble movement.

Heel Counter

This stiff piece of material placed between the lining and upper at the heel of the shoe helps retain its shape.

Squeeze the heel of your shoe. It should retain its shape, but not collapse. Too soft, and you have no ankle support. But if the heel counter is too ridged, you may get blisters.


A Last is a specifically shaped foam used to create the shape of a shoe. Every last is designed for a specific purpose, for an individual type of activity. You can get female-specific lasts which have a slimmer mid foot or heel area, one’s dedicated to wider feet, or when low profiles.


This 4-season boot has a semi-stiffened mid-sole and has a more supportive upper. Good for hillwalking and light crampon-use, but not a true mountain boot.


Less flex than a B1, a B2 rated boot has more supported mid-sole, higher ankle profile and is able to fully take a crampon with heel-clip bindings.


This true mountain boot has a fully ridged construction and has the capacity to take heel clips and wire toe balls. B3 boots are generally not suited for everyday hill walking and should be reserved for glacial walks, high altitude mountaineering and hard ice climbing.

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