Having bought the ZWO off axis guider from FLO whilst down at Kelling Heath Star Party, I initially struggled to get it to work, which was definitely down to my lack of experience in setting up an OAG.
I didn't realise how critical the focus seems to be, and also the positioning of the prism, with only the slightest adjustment making a lot of difference. This focuser makes the job much easier and gives super precise control over the focusing of the camera - in this case an ASI290 mini guide camera, superb build quality too.
First class service as always from FLO!

Nice helical, non rotating focuser. I have fitted this to my 50mm William optics guide scope in place of the rotolock and it makes focussing the guide scope a breeze. Nice and smooth, no rotation, locking screws to secure the focus point.

Nicely made with a lovely smooth action, I bought this after difficulty focusing a guidescope accurately so added this with a spacer and now have perfect focus.

If you've tried to adjust OAG focusing in the past with an alan key in the dark you will know how annoyingly tedious it can be and the worst thing that can happen is the camera and OAG fitting can just fall off to the ground if you don't support it while adjusting.
With the Helical Focuser getting parfocal is much easier and faster:
1. Use a Tablet with ASICAP, connect an OTG to both the Guide and imaging CCD.
2. Focus the Imaging CCD with the main focuser.
3. Switch ASICAP to the Guide camera, and focus the guide with the helical focuser.

All complete in just about a minute or two.

This is a really great bit of kit. Nice and sturdy, feels high quality as soon as you pick it up. Threads are nice and clean and the movement is beautifully smooth but with enough tension to make small adjustments easy. I'm not sure why the graduations go all the way to 9 because the adjustment is limited fro 0-6 which I guess are tied to the 6mm stroke. Maybe the small screw allows you to release and reset the location of the markings but i dont see mcuh point.

But that does not take away from what is an excellent, well built focuser.

It works !. Took me no more than 40 seconds to match my focus - ok maybe 1 minute 40. Worth every penny !