UMB-1 Mattebox Clamp On Ring (143-95mm) - 212800 is a clamp on reduction ring for converting the Base or Swing Away version of the Universal Mattebox into a Clamp On version.
Specifications:
Weight: 90.7 g (0.2 lbs)
Dimensions: 152.4 x 127 x 152.4 mm (6 x 5 x 6 in)