Kupo Pivoting Solid Aluminum Die-Casting Boom Arm Clamp with Plastic Cardboard Insert (Black)The Kupo Pivoting Boom Arm Clamp allows you to use a C Stand riser section as a boom arm. It is constructed with solid aluminum die casting and features a plastic cardboard insert that can fit a tube size from 1. 2 to 1. 4 inch in diameter. Versatile Use With a 1 1 8 inch male pin and a 5 8 inch female receiver, the attachment of a clamp can fit into the junior receiver or mount on the baby pin, which gives greater flexibility and adjustment.