Mount Sight Set Mossberg 500/590

Caliber 12/76 (12GA 3), Shotgun Mossberg Model 500 and/or 590 with Barrel Diameter 0.840/21.4mm to 0.860/21.8mm fits not Models with Heavy Barrel example Model 590A1, Ghostring Rail Sight Set with Banded Front Sight Dot White, Ghostring Sight Steel height and side adjustable, mount aluminium black weaver/picatinny style, with fastening screws, 100% Made in USA, Code MB-4001R-1 XS Sights USA. Rework is perhaps necessary - professional installation recommended - price valid only for 1/one Mount Sight Set Code MB-4001R-1!Fits not Model with Heavy Barrel or barrels with front sight base!