Item description:Zero Recoil mounting for 11mm prism rails, suitable for rifle scopes with diameters of 25. 4 and 30 mm. Nearly 100% elimination of recoil forces for the riflescope and 100% repeat accuracy due to integrated centering pin. This makes it possible to use cheaper rifle scopes on powerful air rifles. Integrated 1 mm forward tilt, extremely firm fit due to long rail with integrated stop pin.