Monstrum Side Saddle Shotgun Shell V2 Holder Compatible w/ Maverick 88/Mossberg 500/590/Shockwave Series Shotguns Black. Built for use with Remington 870/TAC-14/1100 Series shotgun platforms the shell holder accommodates up to six 12 gauge shotgun shells. Unit installs into the pin holes on the side of the receiver with no additional gunsmithing required. Not compatible with other shotgun models. Specifications for Monstrum Side Saddle Shotgun Shell V2 Holder: Manufacturer: Monstrum Color: Black Features of Monstrum Side Saddle Shotgun Shell V2 Holder Built for use with Remington 870/TAC-14/1100 Series shotgun platforms. Unit installs into the pin holes on the side of the receiver with no additional gunsmithing required. Accomodates up to six 12 gauge shotgun shells. Not compatible with other shotgun models. Package Contents: Monstrum Side Saddle Shotgun Shell V2 Holder What firearm models does the manufacturer say Monstrum Side Saddle Shotgun Shell V2 Holder is compatible with? The manufacturer says that Monstrum Side Saddle Shotgun Shell V2 Holder is compatible with Mossberg Maverick 88 Mossberg Model 500 Mossberg Model 590 Shockwave Remington Model 1100 Remington Model 870 20 Gauge Remington Model 870 TAC-14 12 GaugeMonstrum ZH140: Side Saddle Shotgun Shell V2 Holder Compatible w/ Maverick 88/Mossberg 500/590/Shockwave Series Shotguns Black