PROTO® 1/2″ DRIVE RATCHETING HEAD MICROMETER TORQUE WRENCH 30-150 FT-LBS, W/NIST CERTIFICATE CALIBRATED TO +/- 3% IN CLOCKWISE DIRECTION AND +/- 6% IN COUNTER CLOCKWISE DIRECTION. CALIBRATION IS ACCOMPLISHED BY MECHANICAL LOADING OF EACH WRENCH IN A HORIZONTAL POSITION, AND PERFORMING A THREE CLICK TEST AT 20%, 60% AND 100% OF MAXIMUM INSTRUMENT CAPACITY. CERTIFICATION DOCUMENTS TRACEABLE TO N.I.S.T. (NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY). MANUFACTURED TO MEET PRECISION/HIGHLY ACCURATE APPLICATIONS SUCH AS MILITARY AND AEROSPACE.