One (1 mm in diameter) in the set purchased over 20 years ago was broken at work mistake, so I bought it as a supplementary one. It is exactly the same length as the original one, and it fits perfectly in the case. It was written with the same material HSS. I am always very sorry for the variety of Monotaro's assortment.
When tapping bolt holes of 8 mm - 1.25, you can usually pilot holes with a 6.8 mm drill, but in case the other is made of aluminum, it is slightly bigger, there are times when the bolt is slightly rattled when you put the bolt. In such a case, if you drill a prepared hole with this 6.7 mm drill, it is very convenient. However, it is a bit tight to put a tap, so be careful and it is also essential to use plenty of tapping oil.