Black River Manufacturing SBS Benelli M4/SBE 3 6 Round Magazine Extension Kit Carbon Fiber. This is a complete kit. The magazine tube kit comes with everything you need. WHAT'S INCLUDED: magazine tube picatinny magazine tube clamp extended spring and follower. Specifications for Black River Manufacturing Carbon Fiber SBS Benelli M4/SBE 3 6 Round Magazine Extension Kit: Manufacturer: Black River Manufacturing Color: Carbon Fiber Fabric/Material: Carbon Fiber Magazine Capacity: 6 Round Gun Make: Benelli Gun Model: Benelli Super Black Eagle III Benelli M4 Gun Type: Shotgun Package Contents: Black River Manufacturing Carbon Fiber SBS Benelli M4/SBE 3 6 Round Magazine Extension Kit What firearm models does the manufacturer say Black River Manufacturing Carbon Fiber SBS Benelli M4/SBE 3 6 Round Magazine Extension Kit is compatible with? The manufacturer says that Black River Manufacturing Carbon Fiber SBS Benelli M4/SBE 3 6 Round Magazine Extension Kit is compatible with Benelli M4 Benelli Super Black Eagle IIIBlack River Manufacturing BREMTCFSBS: SBS Benelli M4/SBE 3 6 Round Magazine Extension Kit Carbon Fiber