Teng Tools (named after a powerful 12th century folk hero) specialises in a range of mechanics hands tools to suit the price conscious professional user & the quality conscious DIY enthusiast. The Tools have been designed to Tengs own specifications, which meet or exceed British European or federal standards. A professional, matt chromed bi-hexagon socket produced in accordance with ISO9000 & AS954 specifications for increased torque & reduced risk of rounding fasteners. Size 16 mm. Length 38 mm. 1/2 in. Square Drive.