BikeParka Bicycle Cover Style Stash - Color Pavement Grey Polyester Ripstop fabric as standard. It outperforms nylon as it won't stretch if pooled with water. It's also really tough. Polyurethane (PU) coating gives full weatherproofing against rain and wind. Fully seam-taped to protect the stitching and keep any water from seeping through. UPF50+ gives the best possible UV fabric protection, to help stop fabric breaking down in the sun and keep its color. A handy Stuff Sac measuring just 7 inches by 4 inches