One-piece Picatinny scope base is designed for use with Ruger American Rimfire rifles chambered in .22 LR. This 0 MOA rail is engineered specifically to fit the American Rimfire factory scope mount holes on the gun's receiver. MIL-STD Picatinny slot-and-rail spacing accepts Picatinny or Weaver scope rings. One-piece design is precision-machined from billet aluminum. Base is 6" long with a hardcoat anodized finish and includes (4) TORX mounting screws and a T-10 wrench. NOTE: this scope base does not fit the 10/22 rifle. Made in the USA. Genuine Ruger Factory Accessory.