funnily enough, this morning I went to a small factory, here in Italy, where they make ally doors and windows and noticed that that they seemed to be using normal wood router bits to cut the slots for the locks etc., after asking, they assured me that that's exactly what they were! (but obviously good quality TCT),I would just be a little wary of taking too deep cuts with the cheaper ones, as the shanks tend to shear (low quality steel?) this is my experience with wood anyway, one bonus is ,at least, that when they do shear, they don't go flying around the shop or embed themselves in your chest!, they seem to just stop dead in or on the workpiece...Giles