Optical Flat Parallel Bottom 100mm (Flatness 0.00007mm – 0.0000028). Metrology & Measurement standard designed to inspect parallelism and flatness of slip gage blocks, measuring tools & other gauges by interference method. Comes with calibration certificate & manual (in Russian) in original fitted plastic case. Thickness 25 mm (0.98 inch). Flatness of working surface 0.00007 mm […]