A simple and effective tactical upgrade for 12 gauge Mossberg 500 and 590 shotguns with no gunsmithing needed. The ultra-rigid frame incorporates TacStar's proprietary shell holder material to ensure durability and secure shell retention. This innovative lightweight aluminum unit straddles both sides of the receiver and is coated with a non-glare 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 shotgun's bead sight. Keeping six shells at the ready, the low profile design SideSaddle provides extra ammo as well as the extra mounting space you need to take your shotgun to the next level. Also available to fit Remington 870, 1100 and 11-87 Shotguns.