20-Piece Metric Tap and Die Set.

Taps: Tools used to cut or form a thread on the inside surface of a hole. Dies: Tools used to cut or form matching bolts or external threads. Tap wrench and die holder: Handles that securely hold the tap and die pieces during use. This particular set includes 9 taps and 9 dies in various metric sizes, such as M3 x 0.5, M4 x 0.7, M5 x 0.8, M6 x 1.0, M7 x 1.0, M8 x 1.25, and M12 x 1.75.