The endura windchill biblongs come equipped with 600 series pad for added comfort as well as teflon ht treated thermolite which provides extra insulation it also has a windproofbreathable membrane on the front of the leg ankle and crotch panels to keep the wind away from you as well as supportive mesh upper with high stretch lycra straps for comfort endura windchill biblongs features knit fabric with windproof breathable membrane on front leg ankle and crotch panels