The dexshell hytherm pro sock is a mid calf length thermal sock constructed with merino wool terry loop piles that cover the full inside of the sock this provides you with exceptional thermal protection a combination of merino wool and elastric fibre the dexshell socks fit comfortable and snug up to your mid calf the interlining of the socks is made from porelle waterproof breathable membrane along with an inherently moisture wicking performance inner to ensure your feet stay completely dr