The Small Seat Bag is large enough to hold a tube, multi-tool, and a few other essentials. Made from durable poly fabrics. Velcro straps connect to your bike's seat post as well as a cinch sack to keep everything rattle free. Slim profile designed to fit under bike seat PU coated, 600D polyester main body fabric Hook and loop attachment for seat post and seat rails Slim profile designed to fit under bike seat Hook and loop attachment for seat post and seat rails