By the time I am done drilling holes, my 3/8 drill is smoking, no kidding. I use the hole saws that screw onto a drill bit individually. Honestly, they are big teetheded too.
I think they are meant more for wood? Don't know, didn't care. They litterally throw metal shavings all over the place when I cut. Maybe I just got lucky and got a good brand? Lowe's doesn't carry them anymore. Wait, it was Eagle when I bought them.