When you are in very cold conditions, a decent base layer is a must, just like the Rip Curl Key Line thermal trousers. The Key Line Rip Curl men's thermal leggings are made from Dri release micro jersey & feature high wicking qualities to wick sweat away from the skin. These thermal men's longjohns will keep their shape & not shrink & it are also quick dry, allowing you to give them a rinse through at night & be safe in the knowledge that they should easily be dry & ready to wear the next morning.