Extremely affordable and exceptionally well-made, Leupold's Rifleman mounts are precision machined from aircraft-grade aluminum for exceptional strength and lighter weight. These rings are designed to fit 3/8 grooved receives, similar to those found on rimfire firearms and air rifles. 1" Ring diameter Mfg: Leupold SPECS: Rings are 1.06" measured from the base of the ring to the bottom of the scope.