22" long Zerodur mirror flat to tenth wave (lambda/10).Made by Pacific Optical. 1.5 inch face by 3 inch thick. Can be used for cross section autocollimation,calibrate straightness of machine carriage or CMM, or a stage mirror. Capable of being sensed by laser, capacitance sensor, or electronic indicator. Brand new, originally sold for $7000.00.
Will take offers on this,thanks for looking....Terry