Briley Shotgun Magazine Extension Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds w/Sling Swivel Realtree APG TSPA-501SWAPG. The extension is made of tough 6061 aluminum. This allows the tube to have a large wall thickness to improve rigidity without compromising overall weight. The tube screws down on the magazine and locks the fore end in place. The extension is supplied with a magazine tube spring. Specifications for Briley Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds Shotgun Magazine Extension Picatinny w/Sling Swivel: Manufacturer: Briley Fabric/Material: 6061 Aluminum Magazine Capacity: 2 Round Gun Make: Stoeger Franchi Benelli Beretta Gun Model: Stoeger M3K Stoeger M3000 Stoeger M3500 Franchi Model 912 Beretta A300 Beretta A400 Xtreme Beretta 1301 Competition Benelli Nova Benelli SuperNova Beretta Tx4 Storm Beretta A350 Beretta A391 Xtrema II Features of Briley Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds Shotgun Magazine Extension Picatinny w/Sling Swivel Benelli Nova and Super Nova Beretta 1301 Comp 1301 Competition Pro A300 Xtrema A350 A400 Extreme Unico Extreme Plus Lite Extrema I & II TX4 Franchi 912 Vairomax Stoeger 3500 3000 M3K Package Contents: Briley Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds Shotgun Magazine Extension Picatinny w/Sling Swivel What firearm models does the manufacturer say Briley Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds Shotgun Magazine Extension Picatinny w/Sling Swivel is compatible with? The manufacturer says that Briley Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds Shotgun Magazine Extension Picatinny w/Sling Swivel is compatible with Benelli SuperNova Benelli Nova Beretta 1301 Competition Beretta A391 Xtrema II Beretta A400 Xtreme Beretta A300 Franchi Model 912 Stoeger M3500 Stoeger M3000 Stoeger M3K Beretta Tx4 Storm Beretta A350Briley TSPA-501SWAPG: Shotgun Magazine Extension Beretta Auto/Benelli Pump/Franchi 912 Variomax/Stoeger 12 Gauge +2 Rounds w/Sling Swivel Realtree APG