This 3/2mm hood is constructed of 3mm neoprene over the head and the bib is 2mm neoprene. The bib helps seal out water and keep the hood in place when worn with a wetsuit. All seams are glued and sewn for maximum comfort, durability and exceptional warmth. The flow vent in the crown of hood vents trapped air and regulator exhaust while SCUBA diving. The hood may be worn with or without a diving mask and has the added benefits of helping you manage your hair and adds UV protection.Layer with a fullsuit and you have an instant hooded suit.