Mirror is in excellent condition, Pyrex, new coatings, no scratches. I bought it and was told that it is 1/8th wavelength error, but it was supposed to be an F6 instead of an F8 (7.95). I presume it would be ideal for planetary viewing. To be honest, I don't have a foucalt tester, but I did measure it with a flashlight, and the spot on the wall was extremely sharp-- I know that's a poor guess as to whether it is a quality mirror. Unfortunately, I was looking for something a little shorter focal length. $300.00 including shipping or will trade for 10" F6.