99extra Underwear Men's 4 Color Stripe Ice Silk Skinny Boxer Briefs 95% Ice Silk/5% Spandex Imported Ice Silk is a term given to silk that is derived from milk. the fabric with a rich, velvety texture and feels very luxurious on the skin Ice Silk Fiber is more soft, light, expensive than cotton fiber Very important: Acidic or alkaline laundry detergent will destroy "Ice Silk fiber", it only be used neutral detergent. Doctor advised, a underwear don't use more than 6 months, it will become very dirty although you repeated wash it