This 77 to 114mm Threaded Adapter Ring for Clamp-On Matte Box from Bright Tangerine is essentially a step-up ring that allows you to mount a clamp-on type matte box to your lens with a filter thread diameter of 77mm. However, this adapter features a rear projecting 114mm ring, as opposed to most other step-up rings that project forward.
The adapter allows you to mount your clamp-on matte box closer to the front of your lens, reducing the possibility of vignetting with wide lenses. However, its design precludes using it to mount filters on your lens. The adapter features a step cut that allows you to use it with the Bright Tangerine Black Hole adapter. Please note the Black Hole adapter and matte box are not included with this item.