Of course I understand my products. If I don't I wouldn't be selling them. Like I mentioned earlier you have to try these to know the difference between them. I have drilled/slotted rotors for my own car and I can tell the different. My customers put these rotors on they called me back telling me they worked great brake really good. Do you think I'll still have this business going on if this drilled/slotted rotors don't work? Y do you think a lot of people are interested in these. These are performance brake rotors they work.