Since each firearm manufacturer has their own proprietary mounting rail design, each ring model must be machined to exacting tolerances for proper fit and function. Because of this, the Warne Tikka Rings are able to fit right onto the receivers dovetail with no need for a mounting base.Features : Tikka specific recoil pin for positive engagement of ring to receiver dovetail ,Uses 4 Torx style T-15 socket cap screws, 25 in/lb. of torque.,