This B2-Duo Sliding Screw-Knob Clamp from Really Right Stuff has mounting surfaces on the top and bottom of the clamp that mount onto camera bars and rails in a parallel orientation. Lens plates and dovetail telephoto lens feet mount the same way, but a camera should utilize a camera bar to position itself in the same manner.

The main locking knob controls both clamps, and the primary clamp holds camera plates, L-brackets, lens plates, and dovetail telephoto lens feet. At the same time, the secondary clamp holds onto camera bars and multi-purpose rails. Besides the main locking knob, there are two thumb screws that also work independent from the main screw-locking knob and lock the second clamp. Having this feature also allows the clamp to move up or down on a camera bar or multi-purpose rail, which is a very useful feature for macro photography or as a nodal slider for a telephoto lens.

The B2-Duo Sliding Screw-Knob Clamp accommodates only Really Right Stuff or Wimberley camera plates, lens plates, multi-purpose rails, and camera bars, because the main locking knob controls both jaws at the same time, and the accessories have to be the same external dimensions in order to fit. The CNC machined 6061-T6 aluminum dual clamp has a Type II black anodized finish. Index marks are laser-engraved on both sides of the clamp so a position can be repeated.

Mounting Surfaces on Top and Bottom    Accepts Only Manufacturer's Accessories    Laser-Engraved Scales on Both Sides    Used as a Macro Slider    Nodal Slider for a Telephoto Lens    CNC Machined 6061-T6 Aluminum    Type II Black Anodized Finish

Dual mounting surfaces on the clamp

CNC machined 6061-T6 Type II black anodized aluminum

Index marks are laser-engraved on both sides of the clamp

Two thumb screws, which lock the top clamp and it is independent from the main screw-locking knob

The B2-Duo clamp only accommodates Really Right Stuff or Wimberley camera plates, lens plates, multi-purpose rails, and camera bars

Related Questions and Answers

Q: 1. how wide are the three strap bosses? Will a 1" strap fit?

A: The side lugs of the Really Right Stuff B2-FABN Screw-Knob Clamp with Strap Bosses (38mm) will fit a 0.70" strap, the front lug is 0.98" max, and both are 0.125" thickness maximum.

Q: 2. I want to mount this on the top, moving rail of a Manfrotto 454 Macro Focusing rail to accommodate a l-bracket attachment of the camera body. Does the tightening knob clear the bottom of the clamp when mounted on a flat surface? Also, will the anti-twist tabs fit into the 1/4" slot in the 454 top rail?

A: Good question. Thank you. There is not enough clearance to accommodate functionality of the knob when attempting to mount it with the anti-twist tabs into the 1/4 20 slot.

Q: 3. Will this fit on a IFootage Cobra 3 C180F-P?

A: Yes, the Really Right Stuff B2-Pro-II 60mm Screw-Knob Pro Clamp can screw into the Really Right Stuff B2-Pro-II 60mm Screw-Knob Pro Clamp.

Q: 4. Is this compatible with Manfrotto MHXPRO-BHQ2?

A: You may consider purchasing the Desmond DBAD Female to Male Boss Adapter for Select Manfrotto Heads, B&H # DEDBAD, to connect the Really Right Stuff B2-Pro-II 60mm Screw-Knob Pro Clamp to the Manfrotto XPRO Magnesium Ball Head with 200PL-14 Quick Release Plate.

Q: 5. Can this be fixed on a Sirui L20S Monopod / Tripod head...?

A: Yes it will technically screw onto the top of the sirui baseplate but it will be off center.

Q: 6. Will this fit on the IFootage Cobra 3 C180F-P?

A: Really Right Stuff B2-mAS Screw-Knob Clamp has a 1/4"-20 female screw and iFootage Cobra 3 Carbon Fiber Monopod with Pedal-Release Mini Tripod Base has a 1/4"-20 Male screw so it should screw in. If you need any help, please feel free to start a live chat during business hours. An expert from our Pro-Photo department can virtually guide you over live video in the store. https://bhpho.to/3MLX2vU

Q: 7. Can this clamp be mounted on another clamp to be used to change the direction of the rail's orientation?

A: Yes, this is possible, but depending on what equipment you plan to mount and the knob size on the other clamp, there could be interference, though many configurations should work.

Q: 8. What is the diameter of the top plate?

A: The manufacturer does not mention this information. This is a Arca Swiss mount so you will need a Arca style plate for compatibility. https://bhpho.to/3q0MG1v

Q: 9. Can you use the Peak Design Quick release plate on this?

A: Yes, the Really Right Stuff B2-mAS Screw-Knob Clamp with 1/4"-20 Screw (38mm) should be compatible with the Peak Design PL-S-3 Standard Plate (BH #PEPLS3), because the plate uses the same Arca-Type quick-release design.

Q: 10. Can I mount this to a video tripod, like a Sachtler or Miller?

A: Whether you can mount the Really Right Stuff B2-Pro-II 60mm Screw-Knob Pro Clamp on your existing head will depend on the connecting method on your head. This clamp features one threaded 3/8"-16 recessed center socket flanked by two threaded 1/4"-20 recessed center sockets, the RS-Pro-II can be mounted from beneath directly on a tripod head platform, or from above using 1/4"-20 or M6 screws.