Although it became correspondence from m4, the tap purchased at the same time can not be firmly fixed and it is in a state of loose state. I could use it properly in m6, but I was sorry though I made it.
As for the TRS-4, as shown in the posted photograph, the chuck shape is different only for this type. Since the insertion slot is square, the tap does not slip and is retained. It can also be recommended because the material is also good quality cut-out material. Originally I bought TRS-1 for the purpose of 4φ, but changed and confirmed.