However, once I started using them, I realized (I think) that these beats are for "amateurs". The lower part of the nozzles between the grooves (at least I didn't have them) was not very well finished, which could lead to "dragging" of the workpiece during use. The more I use them, the more they wear out. For this reason, however, I would recommend it to laypeople who do not deal with routing. I gave them 4* because of the relatively low price compared to the better designed (and more expensive) more established manufacturers.