Fourth Element Xerotherm Vest The Xerotherm is the ultimate base layer system for dry suit scuba diving. It can be used either on its own under crushed neoprene or under a Thinsulate to augment a diver's existing thermal protection. Constructed from Polartec Power Stretch fabric which has been used on several Everest expeditions, the Xerotherm is the most effective next to the skin garment for ensuring warmth & comfort in demanding environmental conditions. The Xerotherm is made from the fastest wicking fabric in existence. Moisture is moved away from the skin. Air, which is a far superior insulator, is held at the skins surface. This dramatically reduces conductive heat loss from the body. Worn under membrane suits, as a base layer beneath existing thermal protection, the Xerotherm significantly improves a diver's warmth & comfort. Under crushed neoprene suits the low volume, high thermal performance of the Xerotherm provides outstanding protection without loss of freedom of movement.