This dual-sided follow focus has a 1:1 hand wheel-to-gear ratio.  It attaches to both 15mm LWS and 19mm rod supports by snapping onto the rods.

Dual-sided follow focus body
(1) 15mm LWS rod adapter
(1) 19mm studio rod adapter
(2) Hand wheels
(1) Hand wheel extension arm
(1) 300mm focus whip
(1) Follow focus speed crank
0.8/64T, 0.8/38T, 0.8/43T, 0.6/64T, 0.5/78T follow focus gears