SPECS: Steel, black, matte finish. Front Sight - Standard tritium dot with white ring, ¾" (19mm) high from top of barrel. Rear Sight - Base, 1½" (38mm) long, ¾" wide, 1" (25mm) long. Small aperture I.D., 3⁄16" (4.8mm); large aperture I.D., 7⁄32" (5.6mm). Fits Remington 870, 1100, 11-87 shotguns with .860-.885" (21.8-22.5mm) muzzle diameters. Rear sight requires drilling and tapping.