what is shank;
A shank is a supportive structure that sits between the shoe's insole and outsole, and runs underneath the arch of the foot. The shank supports the foot and is what gives a shoe structure. Shanks can be made from a variety of materials, including steel, plastic, fiberglass and Kevlar. They're mostly found in work boots. They are what gives the boots their shape, and they stiffen the outsoles for a more stable fit.