Black River Manufacturing Picatinny Magazine Tube Clamp Black. This clamp is not a cheap latch molded part its machined from a single piece of aluminium making it extremely durable. Specifications for Black River Manufacturing Picatinny Magazine Tube Clamp: Manufacturer: Black River Manufacturing Fabric/Material: Aluminum Color: Black Gun Rail: Picatinny Package Contents: Black River Manufacturing Picatinny Magazine Tube Clamp 2 bolts Black River Manufacturing BRMTCP: Picatinny Magazine Tube Clamp Black