Completely gear-driven design for slip-free, accurate, and repeatable focus movement * Universal 12mm*12mm focus whip (not included) can be inserted * Mounts onto 15 mm Rod Support (60mm center to center difference). * Gear drive can be mounted from both sides. The white mark ring is made of magnet material. It can be detached or attached very easily and quickly on metal-made follow focus * Compatible with industry standard 15mm rods