The ARRI FF-5 HD Pro Set is a complete follow focus kit including an HD follow focus base, left- and right-sided standard focus knobs, two drive gears, one speed crank, one short whip, and 10 marking disks. The FF-5 HD snaps onto 15mm lightweight support rods, or use a bridge-plate adapter to mount to 15mm or 19mm studio rod systems. With a gear ratio of 1:1, the FF-5 HD is designed for smaller video lenses, with one turn of the focus knob resulting in one turn of the focus gear.
https://www.bhphotovideo.com/c/product/1288741-REG/arri_k0_60146_0_follow_focus_ff_5_hd.html
