Keep an extra 6-rounds of 12ga shells handy with this easy-to-install black side saddle shell holder for your Mossberg 500 / 590 / 590DA / Mavrick 88, or Remington shotgun. The 6 round polymer shell carrier slides onto the black anodized aluminum mounting plate which attaches to the side of the receiver. That means the 6 shell carrier just slides off if its not needed. No gunsmithing required. Kit includes longer cross bolt/s, mounting plate and screws as pictured. * select which option you want; - 1) Mossberg 500 / 590, Mavrick 88. SOLD OUT or 2) Remington 870, 1100, 11/87.