I got a new die grinder today (bottom one). My brother had given me the top one (a Harbor Freight special) as a gift. Although the sentiment was nice, it may be the worst tool I've ever encountered. It uses a ton of air, but has almost no torque. The metal casing gets really cold after using it for a few minutes. On top of that, the collet is supposed to hold .250 inch shank tools, but the hole in the collet is only about .230 inch diameter. I had to file down the shank of my home made ScotchBrite mandrel for it to fit. Since I've got a replacement, I think I'll send this one to my brother so he can really appreciate what a fine tool it is. (NOT! :-) I fully intend to harass my brother about this for a long time to come. :-)
I also received a new ScotchBrite mandrel and some coarser ScotchBrite wheels in the mail.