- Heavy duty marine grade fabric - 100% Waterproof - UV Resistant -Covers are designed large enough to fit just about any trailer jack. Treated with top-quality thickened 600D 100% Polyester Fabric Material, DryWraps tongue jack cover offers a higher tear strength than traditional covers, lasting for years. Not only fading-resistant, this RV jack cover also provides waterproof coverage while maintaining breath-ability for the health of the electric jack components, keeping the casing, switches and lights dry and clean and prolonging their original appearance.