I have a 3.1" secondary elliptical diagonal mirror complete with holder. Both are from astrosystems. The mirror has performed excellently on a 25" scope. There is no spec documentation for the mirror as Randy was not sending out such with these mirrors at the time it was purchased. However, as most of you know, Astrosystems only deals with quality products, it is fine pyrex, has no blemishes, performed great (my eye) and is mounted and ready to go. The holder has the 4 set thumbscrews, collimates easily, and holds collimation well. I am only selling it because this 25" primary really needed a larger 3.5" secondary which I now have mounted (with Astrosystems holder).
A new set would cost $190 plus. I'll tke the first $150 or best offer I get ovr $100 within the next week, and I'll cover shipping.
Thanks for looking,