Mesa Tactical SureShell Aluminum Shotshell Carriers with Rail combine a shell carrier with a MIL-STD-1913 (NATO STANAG 4694) Picatinny rail that accepts optical, sights, lasers or accessories. These shotshell carrier/rail systems mount via a “saddle” style method (Remington shotguns) or by using the drilled and tapped holes on top of the shotgun’s receiver.