The ABCSF Tool roll is handmade in San Francisco out of 1000d Cordura fabric and industrial strength velcro. It fits up to a 29x2.3 bike tube(mountain Roll), 1 C02 cartridge, tire levers, and a small multi-tool. Simply put your essential tools in the pockets, fold over the flap, roll it up, then strap under you saddle rails. Perfect for mtb's with dropper seatposts. In the unfortunate event of a flat tire, remove the roll from the saddle, unroll the bag and have full access to your tools in a nice and organized package where your tools never touch the ground. No more jamming all your tools in your boring, average seat bag.