Coldpruf First Layer Fire Retardant Base Layer offers supporting comfort and confidence during activities where fire retardant wear is appropriate. Designed with the comfort of a single layer, waffle knit fabric, consisting of 55% modacrylic and 45% combed, ring spun cotton. Tagless labeling, non-binding cuffs. Top has an extended tail for secure fit. Bottoms feature front & back rise, with gussets and comfort logo waistband. HRC1 Category Rating.