Bought this to use with my new ASI1600 and 8 filter EFW. Fits perfect, very secure with all of my EOS lenses. Not had a chance to use properly but have rigged up off my mount and got focus perfectly.

Having tried two other EoS adapters which have proved less than satisfactory I purchased this one with some trepidation. So far I am well impressed. The adapter fits to the lens better and more rigidly than any of the other adapters I've used with no discernible droop/sag or misalignment. So far I've only used it with a well known 135mm lens; the supplied spacers had to be supplemented to get the correct spacing to achieve focus but in every other respect this is a quality piece of kit and a bit of a no-brainer if using a Canon fit lens with a ZWO filter wheel and camera.