This is a true Speed Crank. The knob swivels, making long and fast focus pulls smooth and fluid through several revolutions. It is the only solution we know of for large barrel lenses with a long travel to the focus ring.
Our unique design features a secure locking mechanism on the follow focus side, ensuring that the speed crank doesn't slip out at a critical moment. Fits any standard ARRI (12mm square) follow focus knob.