Check the listing for details. Glass Optical Flat Parallel Set 15 mm.. Condition: New – Open box. Listed at 42.00 USD. A description of all the exhibited items is made as objective as possible. In the specification, there are technical, physical and other characteristics. Are listed all defects and deficiencies. I am always ready to answer your questions honestly and impartially. Plane glass plates are designed to test the flatness and parallelism of measuring surfaces of the interference method. Comes with calibration certificate in original plastic case.Diameter - 30 mmHeight - 15,62 15,75 15,87 16,00 Other sets can have different values (nearly these) height. Measurement range of micrometers - 0-25 mm.Discount for the combined shippingI will add a tracking number in EBAY Delivery times depend on courier services, and not on me. "Please do not shoot the pianist. He is doing his best."Oscar Wilde .