The only fabric that belongs in your boots is your socks. Hot Chilly's Micro-Elite Chamois Boot Tech Tight Bottoms for men are engineered with soft microfiber MTF (Moisture Transfer Fibers) yarns combined with spandex for a body fit that stretches and moves with you. Bio-Silver antimicrobial yarns to help control odor. The fabric of this midweight base-layer is also slightly brushed on the inside for added softness, comfort and warmth. Features: Features Hot Chillys(R) linear flocked logo Flat seam construction to reduce bulk and abrasion Covered elastic waistband for added comfort Gusset eases movement and reduces seam bulk Engineered boot tech length eliminates bulk inside boots UPF: 30+ Bio-Silver Anti-Microbial properties Moisture transfer fibers Midweight: Medium warmth Body Fit