Stanley J6104ACERT Proto 1/4-inch Drive Torque Screwdriver 4% 20-100 in-oz. - CERT Calibrated to 4% of torque reading, clockwise at 20% to 100% of full scale. 1/4-inch Square to 1/4-inch Hex Adapter included for use with insert bits. Industrial heavy duty design. Aircraft grade aluminum. Aircraft quality spring. Positive self locking lock ring. Floating three point reaction for repeatability. Laser marked easy-to-read scale. N.I.S.T. (National Institute of Standards and Technology) traceable certification supplied with J6104ACERT. Meets or exceeds ASME B107.14M.