Precision optical flats, complete set
One 3 inch diameter by 0.625 thk, Felt Polished to 1V, 1C
Two 2 inch x 0.625 thk, FP to 1C, 2C
One 2 inch x 0.625 thk, FP to 3V, 3V (small chip in the corner)
Manufacturer: The Van Keuren Co.

Informational: the accuracy of optically flat surfaces is recorded in
  millionth of an inch followed by either "V" (Convex) or "C" (Concave).
Example:3V = 0.000003 inch convex
All for $400