The Tilta Rubber Donut Backing Ring for MB-T04 and MB-T06 mounts onto the rubber donut that fits into the matte box and enables a snug fit for your lens, preventing light from leaking around the back of the lens and flaring any filters in the matte box. This ring is not suitable for use as a clamp-on ring.
Prevents light from behind the camera leaking between your lens and matte box and degrading your image
UPC: 690770700080