I would like to sell two 8 3/8" diameter by 3/4" thick flats. These flats are in excellent condition and probably figured to better than a 1/4 lambda. They can be used as coelostats or heliostats or ground into reflective objectives. The glass "looks like" BK7 but I am not certain. Asking $70 each (including shipping in the CONUS. Thank you.