Vocas 105mm to M72 Threaded Step Down XL RingVocas 105mm to M72 Threaded Step Down XL Ring When using a matte box as clip on, step down rings can be necessary, with or without thread. This XL ring is required when using a MB 2XX matte box (with 105 mm front diameter) as a clip on on a lens with internal M72 thread. The shape of the ring is XL for compatibility with large lens fronts such as the Sony HVR 270(S).