Manfrotto 035RL Super Clamp with Standard Stud
Description (from B&H): The Manfrotto 035RL Super Clamp is made of lightweight cast alloy. The Super Clamp is a very versatile tool and it holds just about anything: cameras, lights, umbrellas, hooks, shelves, plate glass, cross bars, even other Super Clamps.
The Super Clamp can be securely mounted on any tube from 0.5″ to 2.1″ and is supplied with a unique wedge insert for clamping onto flat surfaces. A built-in socket allows the use of over 30 attachments to hold anything from backgrounds to lighting fixtures.