Seamless™ Follow Focus Gear for Leica 50mm f2 Summicron - R I (Version 1) LensThis gear fits the Leica 50mm f 2 Summicron R I lens (serial numbers 1940501 2760150). Standard gears are designed specifically to fit this lens and is compatible with any standard 0. 8 Module follow focus. The gear sits 3 6mm high off the focus ring of your lens for a clean, low profile gear that slides smoothly onto your lens and into your current lens case. The gears do not have to be removed after each use although you can if you like. Each gear