Shank (footwear)

In a boot or shoe, the shank is a part of the supportive structure between the insole and outsole. The presence of a shank is crucial to the functionality of mountaineering boots as they diminish the load incurred by the wearer’s feet and calves over the course of an ascent. Traditionally constructed of steel, contemporary shanks are more commonly made up of less heat conductive but equally rigid options such as fiberglass and Kevlar. The rigid nature of these materials contributes a protective element to the footwear into which they are integrated, helping shield the wearer’s feet from puncture wounds and stone bruises.

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Wikipedia