Semi-dry suits are effectively a thick wetsuit with nearly watertight seals at wrist, neck and ankles and zip. They are typically used where the water temperature is between . The seals limit the volume of water entering and leaving the suit, and a close fit minimises pumping action caused by limb motion. The wearer gets wet in a semi-dry suit but the water that enters is soon warmed up and does not readily leave the suit, so the wearer remains warm. The trapped layer of water does not add to the suit's insulating ability, and any water circulation past the seals still causes heat loss, but semi-dry suits are cheap and simple compared to dry suits, and do not fail catastrophically. They are made from thick Neoprene, which provides good thermal protection, but lose buoyancy and thermal protection as the trapped gas bubbles in the neoprene foam compress at depth. Semi-dry suits are usually made as a one piece full suit with slick inside surface neoprene wrist, cuff and neck seals. Two-piece sets tend to be a one piece full length suit, sometimes described as "long johns", plus accessories to be worn over, under or with the one-piece suit, such as a shortie tunic, which may be worn separately in warm water, but has no flush-limiting seals at the openings. Semi dry suits do not usually include hoods, boots or gloves, so separate insulating hoods, boots and gloves are worn.