Supply of 1 Double Ended Thread Plug Gauge Go And Not Go Of Size M 16X1.5-6H Class With Calibration Certificate From Any Nabl Approved Lab. 2 Thread Ring Gauge Go And Not Go Size M20x2.5--6G Class 1 Set 1 No. Of Go Thread Ring Gauge And 1 No.Of Not Go Thread Ring Gauge With Calibration Certificate From Any Nabl Approved Lab..