Pre-marked Iris rings work with the Teradek RT's Lens Mapping.

Lens mapping allows for auto-calibrating lenses to pre-marked focus rings and accessing configurations at any time with the touch of a button. Pre-marked rings cover multiple lenses, saving time on set from manually calibrating after every lens swap. 

Dimensions: 3.2in x 0.87in x 3.2in (81mm x 22mm x 81mm)
Weight: 18g