"The fourth element Xerotherm is the ultimate base layer for use under a drysuit. The Xerotherm top is the ideal next to skin layer under a drysuit with flat seams and a long body to ensure that no separation between top and leggings develops. Thumb loops keep the sleeves in place whilst donning the drysuit and should be removed from the thumb and pushed back through the wrist seals prior to diving. Made using Polartec Powerstretch originally developed for NASA, the Xerotherm traps a layer of air - a much better insulator than water - next to the skin, keeping the wearer drier and more comfortable. The range is designed to be worn under another undersuit or on its own under a neoprene drysuit. The knit of the Xerotherm fabric produces the fastest wicking effect of any of the products in the fourth element product range. Moisture is drawn out through the fabric along fine fibres and then spreads out over the outer surface. This maintains a thin layer of air next to the skin. This is so effective in the Xerotherm that some wearers report experiencing minor suit leaks during the dive without even noticing until after the dive.