Polarmax knows that if something is working then hey, don't mess with the formula! Double Base Layer is their most Popular Layering Piece! This collection is great for skiing, Hiking, Climbing, Fishing- ALL WINTER SPORTS or if you just want to be warm then look no further than Double Base Layer!!Mid-Weight with flat seam construction for ultimate comfort. 100% Acclimate Dry Polyester. Moisture Wicking, Breathable, Quick Drying. Anti-Microbial/anti-odor protection. Relaxed Fit that feels like cotton. Machine Wash and Dry.