UTG PRO US Made 30mm/2PCs Low Profile POI Picatinny Rings Original Snag-free Contoured Profile with Reduced Weight and Size Machined from 6061 Aluminum Alloy and 4605 Steel with Matte Black Hard coat Anodizing Low Profile Precision Optics Interface (P.O.I) Rings Have a 25mm Center Height to Fit Optics with a O30mm Tube, and up to a O49mm Outer Objective Progressively Machined for a Precise Inner Diameter Scope Interface to Achieve a Seamless Ring -to-Scope Interaction Flush-fitting Locking Plate Interface with Dual Spring Loaded Guide Rods and Torx Screw Locking Ensures Secure and Repeatable Zero Hold Precision Milled Integral Recoil Stop Seats into Picatinny Slots Eliminating the Possibility of Forward and Aft Movement From Recoil Vibrations