Please ensure these mounts will suit your application by carefully checking that the tube size and base type is correct before purchasing. 2 Piece Mounts. Base Fitting: 9.5 – 11.5mm (3\8) Dovetails – Most popular size (suits most modern airguns and .22 rimfire rifles). Tube Size: To fit 1 (25.4mm) diameter body tube scopes. Front Lens Size: Up to 56mm – This figure describes the maximum size of the objective (front) lens the mount is designed for when the dovetails are flush with the barrel. Please bear in mind scopes with front PX adjustment will often need higher mounts. Bolt Type: Allen Key bolts – Allen Key(s) Supplied. Clamp Design: Double Clamp (four bolts on each cap). With removable recoil stop pin. Dimension A: 24mm Dimension B: 21mm Sportsmatch offer huge selection of quality mounts – All Made In England!