The Phase 1 Boxer Briefs from XGO are made from a blend of Modacrylic and FR Rayon that meets the ASTM D6413 Standard. These boxer briefs will not melt or drip if exposed to flame. These briefs also feature XGO’s Superior Acclimate that will wick moisture away to help keep you dry and comfortable. Allows for unrestricted movement. Ideal for temps between 40 – 100 F.