Upgrade your shotgun's aiming capabilities with the HiViz M500 Magnetic Shotgun Sight. Designed specifically to fit Winchester Post-1964 automatics and pumps, as well as unported Mossberg shotguns, this sight features a secure magnetic base that attaches easily to vent ribs measuring .437 to .578 inches wide. The bright green fiber optic LitePipe gathers ambient light for a highly visible aiming point in all lighting conditions. Installation is fast and requires no gunsmithing, making it an excellent choice for hunting or clay shooting.