SIZE: S: suitable for head 51-54cm; M: suitable for head 54-57cm; L: suitable for head 57-60cm; XL: suitable for head morethan 61cm; Neoprene COMFORTABLE & FLEXIBLE FIT: the neoprene diving hood constructed with 3MM premium neoprene to give you a flexible, soft and comfortable fit, with form-fitting design helps you less restrictions during water sports, offer you a fantastic snorkeling and surfing experience WARM & PERFECT PROTECTION: the thermal scuba dive hood is UV protection and will protect your head from hurt by sea lice, jellies, coral...etc., and keep warm while underwater, besides, the face seal inner forming rubber layering for better seals with less water absorbs, you can enjoy water safely for longer time (However, kindly be noted Scuba Hood is not a completely waterproof product, but a diving equipment to match wetsuits ) WIDE USE & GREAT GIFT: Slip-on design with smooth flat seam is durable for easy on and off, it can be used for sun-resistant, bind hair and moisturize etc, wonderful for beach, snorkeling, swimming, scuba diving, surfing, sailing, kayaking, canoeing, paddling, rafting...aquatic sports, what a great gift set for mother, father, family, friends, lover...ect HIGH STRETCH & DURABLE: 150% high stretch and excellent recovery, glued and blind stitched for superior strength and durability that will last, dont worry about ripped, we are confidence that it will be a long term partner for you SATISFACTION WARRANTY: The face seal can be DIY trimmed to precisely match unique facial contours, both available for men and women in all size S, M, L, XL, please choose the size according to your head girth and reference to our size chart, However, due to everyones head shape is difference and measuring tolerance 1cm allowed.