I have a BobsCNC E3 CNC router and since the machine is made of wood which can bend under pressure I have not been able to cut perfect squares and circles on acrylic. With these routers I was able to cut perfect squares and circles that don't look like ovals because they go through the acrylic easily and don't put much pressure on the CNC router. I gave them 4 stars because they break easily and I've already broken one. Also, they aren't labeled and you can't tell what size each one is, which would be easy as they come in a nice plastic case with separate slots for each cutter and they could have at least listed the dimensions on the case. Finally, I'd rather pay that price for 10 of the same size than different ones because they break easily, and continuing to buy this set to replace the ones I normally need is a decision that doesn't make financial sense.