I have Zacutos Zipgears for six of my lenses. These are expensive and
I've asked myself are they worth it? Really there was no choice before
Shoot35 came with their version called FLEXIgear. Seams similar right?
Well they are very similar yet not entirely. Zipgears have two parts
which holds the gear strip together, the FLEXIgear has a one piece lock
and it's much easier to assemble.
The FLEXIgears are stiffer than Zipgears and I tightened just a turn to have it stick perfectly onto the Canon 70-200/4 lens and it's broad rubber ring.
I have tried lens gears that are bulky and screws onto the lens barrel from all angles and they are nothing I would like to use again. Zipgears or FLEXIgears are much better but the Shoot35 version is cheaper and feels better to adjust and assemble!