The SureFire RYDER 9 Fixed Barrel Spacer is to be used for additional reliability when firing the SF RYDER 9 or RYDER 9M Suppressor on a fixed barrel firearm, typically seen with 9mm carbines and rifles. This is accomplished by reducing the movement of the suppressor when firing. Simply replace the booster spring which comes installed and replace with the SureFire RYDER 9 Fixed Barrel Spacer. Length: 1.25" (3.2cm) Weight: 1.2oz(34g) Construction: Stainless Steel Easy Installation Designed and built in the USA Mfg: Surefire