TacStar Slimline Side Saddle, Black, Fits Mossberg 500/590, 12Ga, Holds 6Rd 1081210 The Slimline Sidesaddle utilizes a non-glare" anodized aluminum backing plate material similar to the traditional Sidesaddle. It is contoured so that it takes up less space on the receiver and has fewer areas that could potentially snag. Additionally" the shell carrier itself is made from a flexible synthetic rubber material which offers durability and weather resistance as well as secure shell retention. Like the backing plate" the shell carrier is also smaller in size than the traditional sidesaddle" adding to its sleek appearance. 12 Gauge Only.