One thing to keep in mind with cut off wheels. Ok.... actually a couple things
1st, do yourself a favour and get a face shield. I've had a coworker buy some cut off wheels for the shop. He didn't pay attention to the rpm speed for the wheels. I didn't pay attention to there rating when installing on my die grinder. They were rated for lower speed then the die grinders we used. Had one shear apart leaving a piece embedded in my neck
Missed my jugular by a couple centimeters.
2nd, Pay attention to the rpm rating for the disc. Make sure and buy cut off wheels that meet or exceed the rpm rating for the tool they are used on. This is from die grinders to chop saws.
3rd, as stated, Pay attention to the material they were intended for. One for aluminum or masonry is gonna give you fits when cutting steel. Like others, I've been there done that
I asked Santa for the better of the two chop saws from harbour freight for when I'm doing metal projects at the house.