Shearling Top Covers add the warmth and comfort of genuine wool shearling beneath your feet. Easily attach to any Tread Labs arch support with low-profile hook and loop. Wool is naturally anti-microbial, keeping your feet fresh. Designed with 10mm of wool shearling and backed by 2mm of open cell polyurethane foam, Shearling Top Covers compress underfoot, providing the same fit as our regular 5mm foam top covers.