Heat treated steel ratchet head. Fully hardened & tempered. Chrome plated for corrosion resistance. Calibration tolerance in accordance with BS EN ISO 6789:2003. Range: 50-300lb.ft, 68-407 Nm. Every wrench is tested & supplied with an individually numbered test certificate. Micrometer type torque range adjustment with scale graduated in both lb.ft & Nm. Flip reverse ratchet mechanism. Supplied in storage case. Model No. AK628