The SureFire SF Ryder 9 Fixed Barrel Spacer is to be used for added reliability when firing the SF Ryder 9-Ti and SF Ryder 9M-Ti suppressors on a fixed barrel firearms, typically seen with 9 mm carbines and rifles. This machined stainless steel spacer with short spring restricts the movement of the suppressor for increased reliability and inherent accuracy when firing suppressed. Simply replace the provided booster spring that ships standard with the suppressor and swap for the fixed barrel spacer.