A metric threading die is fundamentally different because the thread pitch is specified instead of threads per inch, or threads per millimeter. There are generally three types of taps: taper, plug, ...

They are available with tap wench size of 1/4" to 1/2" (6mm to 12mm). Some examples of pipe threading tool specifications include pipe thread die heads of 1/4, 3/8, 1/2, 3/4 and 1 inch, ratchet ...