ARRI Studio Follow Focus FF-4 product page

Arri Follow Focus FF4 and Accessories
The Arri FF-4 was designed for cameras with rotating shutters like the Arri BL, 435 and 535. It’s low profile allows it to snug-up against the camera.
The Arri FF4 Follow Focus slips over the 15mm mini lens support rods or with an adapter, it can clamp-on to the standard 15mm or 19mm lens support rods. (Rod adapter sold separately).