I use these all the time for many fabrication clean ups, welding preparation and finishing up ported cylinder heads and they work well. The mandrels that come in the pack with them seem to break quickly so I stopped using those and use U.S. made longer mandrels that I source elsewhere. Very good value IMHO

What a disappointment! I saw these on sale and jumped on them. I've made several attempts to use them and all have ended in disappointment. The 1/4" shank mandrel just snapped. Maybe I'm running them too fast, but the 1/4" says to me a die grinder should work fine. I don't have the package anymore to see if it specifies a rpm and the website doesn't give this information. I didn't buy these to slowly sand a radius in steel. The sleeves shred and are too tight to fit on the end of the mandrel without more of a battle than I want to deal with.