This ultrarigid lightweight aluminum unit straddles both sides of the receiver and is crafted with a nonglare anodized finish. The top Picatinny rail can mount a variety of accessories yet is designed to sit just high enough to allow continued use of the shotguns bead sight. This rail mount incorporates a Slimline SideSaddle shotshell carrier made of flexible synthetic rubber to keep six 6 extra shells in readiness.This model fits 12 gauge Remington 870 1100 and 1187 models.