Free Fly's heaviest fabric blend delivers the comfort of bamboo with heritage style details. Features Hidden chest snap button pocked lined with midweight bamboo blend Four button snap collar UPF 50+ Sun Protection Bamboo Insulate 29555% Viscose from Bamboo / 45% Polyester Fit: Regular Weight: 295 GSM Care: Turn inside out and wash on cold, delicate cycle. We recommend hang drying. Following these simple steps will extend the life of your garment.