Tilta's 81 to 83mm Seamless Focus Gear Ring allows you to add 0.8 MOD gears to a compatible lens for use with cine follow focuses. This 81 to 83mm size fits virtually all lenses of the same outer diameter. The seamless version is designed with an improvement over Tilta's earlier gear rings in that it's fully closed and requires no screws in order to be secured to the lens. As a result, it attaches to the lens more easily and provides evenly distributed pressure while ensuring zero drifting and accurate focus. It's made of durable, flexible rubber, attaches firmly, and works silent and smooth along 360° of rotation. The MOD rating and 81 to 83mm diameter size are etched out on the inside of the ring.

What is the perimeter/circumference of the focus ring on your lens?

How to measure perimeter/circumference:

Cover the entire focus gear with a slip of paper and pull the two ends together tightly. Markdown where the two ends meet with a pen. Make sure to mark or be aware of both ends.

Spread the paper slip and find the marks. Measure the distance between the two marks with a ruler in millimetres. For example, 255mm.

Divide 255mm / 3.14 (π ) to get the diameter, which is 81.2mm in this case. The 81-83mm ring size will fit your lens.