This is a Warne Scope Mounts Ring known as the Maxima, model 202M.
The Maxima Fixed Ring Series fit Weaver style cross slot bases and incorporate a Warne square stainless steel recoil control key in both the front and rear rings. This ensures a "no slip" positive recoil surface across the entire slot of the base and is capable of withstanding the heaviest of recoil. The Maxima square recoil key also protects against swaging or peening of the bases when used on softer or less durable materials. The Maxima Fixed Ring band is also substantially wider for additional clamping surface around the scope to hold the optic firmly in place.
Features:
Square recoil control key for positive engagement of ring to base
Uses 4 Torx style T-15 socket cap screws 25 in/lb. of torque recommended.