Purchased for use on a 6" RC GSO, as collimation is never super accurate using just a Cheshire and Baader laser. The OCAL was fairly easy to use after some trial and error, and watching their RC collimation video. Best used with a large screen, I find a smartphone works but is too small to get an accurate solution. The USB A to C adapters is too flimsy and was ditched for a better quality adapter I bought separately. Overall good quality build, and the software works very well on Windows and on my Android smartphone.