Reversible Universal Petroff Follow Focus Known to many as Zacuto Follow Focus Reversible direction gear box. No-Tool manipulation. You dont need any tools to change the gear drive from one to the other side or to reverse the rotational direction. Compatible with ALL lenses regardless of the rotational direction The gear box is made not with stock but with custom made helical bevel gears that assure an extremely accurate and smooth no-play (otherwise known as a slop) movement.