Tuff Bladders are different from any other bladder on the market. Over 2x as durable, these bladders have been specifically developed to withstand the abuse of kiteboarding. The big secret to our bladders is stretch. while other bladders are stiff and pop easily, the tuff bladders stretch when put under then quickly go back to their original shape. use Tuff bladders in any kite when you want the toughest, most durable bladder available. The symbol ‘ stands for feet and ” is for inches. These are blanks and do not include valves.