Adapter rings are the link between the lens and the matte box. Each lens will needs its own specific adapter ring.
Separate rubber donut set for flexible donut adapter ring MB-215, MB-216...
0250-0195-01
Separate rubber donut set for Flexible donut adapter ring MB-435 and MB-...
0420-0601-01
Flexible adapter ring kit, 143 mm, for MB-4xx matte boxes.
0420-0601