Semi-dry suits are effectively a thick wetsuit with better-than-usual seals at wrist, neck and ankles. The seals limit the volume of water entering and leaving the suit. The wearer gets wet in a semi-dry suit but the water that enters is soon warmed up and does not leave the suit readily, so the wearer remains warm. The trapped layer of water does not add to the suit's insulating ability. Any residual water circulation past the seals still causes heat loss. But semi-dry suits are cheap and simple compared to drysuits. They are made from thick Neoprene, which provides good thermal protection. They lose buoyancy and thermal protection as the trapped gas bubbles in the Neoprene compress at depth. Semi-dry suits can come in various configurations including a single piece or two pieces, made of 'long johns' and a separate 'jacket'. Semi dry suits do not usually include boots, so a separate pair of insulating boots are worn. They are used typically where the water temperature is between 10 and 20 °C (50 and 68 °F).