I got this mirror (not prism) star diagonal with a celestron refractor I recently purchased new. The diagonal doesn't have any markings on it, so I guess its a generic manufacturer. However, I think this one is much better than a celestron brand prism diagonal I had. I think this would be a good improvement from the poor diagonals that come with some scopes. Perfect condition, not even any set screw marks on it. I'm selling because I also have another (more expensive) diagonal so I don't think I need two. $35, shipping included. Money order or paypal preferred. Thanks for looking.