Mallory and Irvine wore single boots with many pairs of socks. At one point, Mallory reported taking off one of his three pairs of socks, which made the boot fit more loosely and allowed his feet to warm up. The boots had leather soles. At high altitudes, crampons were not used. Instead, nails resembling upholstery tacks were fixed to the bottom of the slippery leather sole to get a grip on snow and ice.