This bone-shaped microfiber sponge will gently clean exterior surfaces without scratching. Many synthetic sponges are made of closed cell polyurethane foam. The material is durable, but the tiny cells tend to hold onto contaminants rather than releasing them into the rinse water. Gritty particles end up being dragged across your vehicle's paint. Upgrade your wash sponge to this microfiber-covered pad that we've affectionately named "The Bone." It maintains the water capacity of an ordinary sponge, but its soft microfiber covering is much safer for your paint.