C-Skins Polypro HDi Long Sleeve Thermal The High Density Insulation fabric used in PolyPro rash vests has amazing thermal properties while remaining lightweight. It also helps to draw water away from the body to keep you warmer. This rash vest can be used as part of your thermal layering system, as a rash vest or as UV protection in hotter/sunnier climates. C-Skins Polypro HDi Long Sleeve Thermal Rash Vest - 2017