Vocas 143 mm to 138 mm Step down ring for MB-435 / MB-436 & MB-455

When using a matte box as clip-on, step down rings can be necessary, with or without thread. This ring is required when using a MB-435, 436 and MB-455 matte box (with 143 mm front diameter) as a clip-on on a lens with a front lens diameter of 138 mm.