4fit Men's Neoprene Weight Loss Sauna Sweat Shirt Long Sleeve 4fit Sauna Shirts is Made by Neoprene which is 1.7mm Elastic Neoprene Performance Fit - Skin tight Pullover no zip design.Protect your hide from rashes & plenty of warmth for serious sweat loss Layer under a full or hooded wetsuit for extra warmth Increase your Mental and Physical toughness