This is my first set of tongue and groove bits. I like them, but they are definitely the scariest bits I've worked with: they are big, so they will cause a lot of vibration! My hand-me-down router and table is really not the best for these and I had to get things good and bolted down before I could safely use them. Even then, I felt there was more slop in the joint than I was expecting. It could be a problem in my setup, (the bits on inspection out of the box seemed well matched). Still, other reviewers have noted that the vibration can cause a slightly larger cut than desired, I'm just not sure in my case. I do recommend seating them absolutely all the way down in the collet (the instructions say it must be inserted 80% minimum, I say go all the way).
Since I don't have the money for a nicer router and table this was all I could get for now, but if you have the money, get the 1/2" shank version, not the 1/4". These heads are just so big, it's scary to think that they are only held on by 1/4" of metal! Also, a variable speed router (so you can slow them down) would be nice. My router is not variable speed, sadly. I probably won't use them too much until I can upgrade to something that is.
Do not even think about using these in a hand held router.
