Ruger Rapid Deploy Rear Sight, Back up Sight, Fits Picatinny, Black Polymer 90415 The custom-designed Ruger(R) Rapid Deploy Rear Sight seamlessly integrates on the Ruger(R) SR-22(R) Rifle" AR-556(R) " SR-556(R)" SR-762(R) and any modern sporting rifle with a same-plane Picatinny rail mounting system. The rear sight can be used in conjunction with most A2-height gas block/front sights. This lightweight" polymer sight is windage-adjustable; folds flat to make room for optics and is spring-loaded to allow for rapid deployment with the push of a button.