The STEELMAN PRO 12-Piece Metric 144-Position Ratcheting Wrench Set was designed to keep you working in tight places where a regular ratchet will not fit but you lack the room to use a regular wrench. The box end features a built-in 72-tooth ratchet whose offset dual-pawls allow it to function with the 2.5 degree swing arc of a 144-tooth ratchet! The open end of the tool features a V cut throat to provide more contact with the surface of fasteners. Also featured on the open end are non-slip grooves that allow you to grip rounded fasteners that normal wrenches cannot. To ensure that the box end ratchet can stand up to hard use they have been tested at up to four times the industry standard for torque strength for box end wrenches. Included in the 12 piece set are 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19mm sizes.