Simon
I have used 2 of the Astrosystems secondary holders on scopes I have built and, like John, I am very happy with their performance. Easy to install, easy to collimate and well made.
I also had a Dewguard that worked fine for a couple of years and then packed it in, not sure why. I simply replaced it with a Kendrick one on the 20" scope. The one I used is here
https://binocularandtelescope.com.au...mm-minor-axis/ and it works fine with a Digifire controller.
Malcolm