Smooth skin neoprene inner at the collar, arm and legs to stick your skin tightly & make sure that much less water comes inside.FULL BODY SUIT - 3mm neoprene diving suit KEEPING WARM.SIZE SELECTION TIPS: please do not choose according to the size you usually wear, and see the product size chart, be sure to take on weight as the first reference factor, followed by height. For occasionally player, suggest 1 size up if you don't want to fall tight. DIVING SUIT ZIP AND NECK DETAIL- Heavy duty YKK Zipper with zipper pull/ hook-and loop closure at back is easy on and off.Ultra Stretch Neoprene: Incredibly Soft Premium Material Has Superior Feel, Flexibility, And Elevates Performance.