The Bone by Cobra - Microfiber Wash Sponge This bone-shaped microfiber sponge will gently clean exterior surfaces without scratching The Bone is a thick foam pad covered in fluffy, soft Cobra microfiber. Rather than the dense loops found in our towels, this microfiber is open-ended to form millions of tiny fingers The fingers gently scrub the surface of your vehicle to remove contaminants, but they will never scratch The pile is deep enough to allow loose grit to migrate into the fibers rather than be dragged across the paint surface Since the fibers are open-ended instead of looped, they release gritty particles into the rinse water rather than holding them within the loops