This 0 MOA scope base is intended for shorter distance shooting or for use with canted scope rings. The rail is engineered specifically to fit the Ruger Precision 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 5.25" long with a hardcoat anodized finish and includes (4) TORX mounting screws and a T-10 wrench. Made in the USA. Genuine Ruger Factory Accessory.