Spitfire Armory - MX Tactical Front Sight Mossberg 500 similar shotguns Clamp is CNC machined from 6061-T6 aluminum with matte black hardcoat anodized finish Designed for STANDARD size barrel, not HEAVY GAUGE. NOT FOR GUNS WITH BREACH MUZZLES (You will need a heavy barrel model with a shim. Contact us as we have a limited number in supply). Use with Ghost Ring MX Rear Sight for complete system (see image) Engineered and made in the USA