The rubber ring fits barely. When I put it on the outer focus ring then the black lock on absolute stop. Therefore, I can not confirm whether it holds at smaller diameters - have since never tried and it will not for the time being. Getting the part there was hard work.
Today I need to find a small tear on the rubber. Well I'm not exactly squeamish to deal with this product - that it has so far held up well. Nevertheless, I will soon be a replacement so I do not order suddenly without stand there.
It would be nice if it would eventually be a version has not just one but a real evert Plastic clip that holds the whole together. But until then, it is - as so often in film production: improvising.
SUPPLEMENTARY 08/29/2013:
I use mittlerweise a second follow focus. Songs no longer exists, the black fuser from a solid plastic but a rubber. As written in the reviews previously, slips this time upwards, so that there is a risk that during the shoot opens the loop and the focus suddenly no longer mitfährt. Although the enclosed reusable cable ties may prevent this, but it is here for a quite cumbersome and the other more of a step backwards rather than an improvement!
But in Lowbutgetbereich one endeavors to for always looking for a solution and so I have found to this problem:
Remedied by a thick rubber band, which to the black rubber holder is wound. This allows these indeed make a difference sluggish, then sit but really fast to the position and not sliding back. Respectively the loop no longer opens.
I simply advise the manufacturer therefore instead of the cable tie two rubber bands from the skydiving which you used for tying the linen to put in with.
Because of retrogression I prefer one point again. I can recommend the product yet. For this money I have been able to find no other Follow Focus.