This Teng Tools tap and die set is ideal for repairing screw threads. Taps cut a thread on the inside surface of a hole, creating a female surface which functions like a nut. Dies, on the other hand, cut a thread on a preformed cylindrical rod, which creates a male threaded piece which functions like a bolt. This 17-piece set contains 7 metric taps and dies of each dimension, a tap wrench, a die stock and a screw pitch gauge. The tools are supplied in a handy storage tray. The TTTD17 tap and die set contains the following:7 x Metric dies: 3 x 0.5mm, 4 x 0.7mm, 5 x 0.8mm, 6 x 1.0mm, 8 x 1.25mm, 10 x 1.5mm and 12 x 1.75mm. 7 x Metric taps: 3, 4, 5, 6, 8, 10 and 12mm. 1 x Tap handle: capacity 3 to 12mm. 1 x Die handle with adjustment screw: capacity 3 to 12mm.1 x Screw pitch gauge.