SIZE: S: suitable for head 50-54cm; M: suitable for head 54-57cm; L: suitable for head 57-59cm; XL: suitable for head 59-62cm; Premium Material--Made of 90% neoprene +10% nylon; featuring flexible, soft and comfortable; snug fit provides a wonderful wear experience,lets you can enjoy the water sports more longer.One size for most adults. Professional Diving Hood--Excellent stretchy; good rebound resilience design makes the diving hood can fits your head better, never worried it will ripped off when you do sports. Full Protect Your Head--The thickness of 5mm neoprene and nylon material can slow down the head temperature loss,effectively to kepp your head warm in the water, also will protect your head from hurt by sea lice, jellies, coral and etc. Applications--Dries quickly,specifically designed for beach, scuba, diving, surfing, snorkeling, paddle boarding, swimming, wakeboarding, coasteering, kayaking, canoeing and other water sports or outdoor activities .