We invented this new Elastic washer when it was pointed out to us, by an artist using a Belmont prototype, that he couldn’t get enough tension from his elastics. With an open back design the elastics slack up a lot. With this new Elastic washer you can replace the rear fiber washer and add this elastic catch. Adding more angle to the washer also adds more tension. Works great on any style frame without a natural elastic catch. Pack of 4.