The Movcam 114:80 mm Step-Down Ring for 114 mm Threaded MatteBox is a threaded ring for threaded 114 mm matteboxes. It screws onto the rear adapter of a threaded 114 mm mattebox and lets you mount a 80 mm lens into that mattebox.
Movcam makes matteboxes in four different sizes -- for 144 mm, 130 mm, 114 mm, and 104 mm lenses. All but the 114 mm are clamp-on. The 114 mm is threaded.
