this is the Quick Release Base, similar to the otto nemenz version of the ronford baker quick release bases (RBQ).
the QRB is compatible with all large size quick release systems like the O’Connor 120mm euro plate and sachtler 35 camera plate.
there are multiple 3/8″-24 threaded holes for a variety of mounting options including the Arri BP9.
the holes in the 4 corners are for a 1/4″ flathead screw. apparently the holes line up to a bungee cam mount.
I also sell the small size (mini-QRB) as well as touch & go plates for both sizes.
Dimensions of the the Quick Release Base:
4-1/2” x 6-3/4” x 11/16″ weight 1lb8oz
Terms for the Quick Release Base:
“available on backorder” items will be available in 1-3 weeks. See “FAQ” for more details.