For winter ops, helo transport, and high altitude ISR ops, these thermal bottoms a critical piece of gear for your load out.These expedition-weight base layer bottoms move moisture away from the skin and dry quickly, providing just the right balance of insulation and moisture management. Four-way stretch and an athletic fit allow this piece to move with you as you scale ridges or post hole through waist deep powder. Use this piece for lightweight warmth during high energy, cool weather activity, or with the matching pullover as part of an expedition-weight base layer system.