Description: 47 pcs/set precision metric gage block set, rectangular,DIN861 grade 1 ----w. tollerance within 0.20um(0.000001m) Marked with serial number and size. Complete standard general certs showing the guaranteed standard tolerance. Meets or exceed Fed. Spec. GGG-G-15C and Conform to MIL-STDD-45662A 18 blocks: .1.005 and 1.01 - 1.19mm in 0.01mm steps 8 blocks: 1.20 - 1.90mm in 0.1mm steps 10 blocks: 1.00- 10.00mm by 1mm steps 10 blocks: 10.00 - 100.00mm in 10.00mm steps Fitted in heavy duty and precision made wooden box.