Precision-machined accessory rail lets you mount optics, ghost-ring sights, lasers, lights, night vision gear, and other tactical accessories on your Mossberg 500/590. Cut to true MIL-STD 1913 Picatinny specs from 6061-T651 billet aluminum. Attaches to factory drilled and tapped receivers using the provided mounting screws. Low-profile design with integral sight channel allows use of front sight when optics/accessories are removed. Extends forward over barrel for maximum mounting flexibility. Skeletonized underside reduces weight without compromising rigidity or strength. Durable, MIL-A-8625 â€œFâ€ Type III Class 2 hardcoat anodized finish for additional strength and superb wear-resistance. Saf Mfg: Hahn Precision SPECS: Aluminum, matte black hardcoat anodized finish. Requires drilling and tapping on early model Mossberg 500. Safety Rail - 9-11/16'''' (24.7cm) long, 13/16'''' (2.1cm) wide, 3/8'''' (9.2mm) tall. Standard Rail - 7Â¼'''' (18.4cm) long, 13/16'''' wide, 3/8'''' tall.