Wow This is one of the best grinders on the market, I have used Hitachi,Makita, Dewalt etc for over 20 years but this Metabo thing just keeps going and going. I have been through at least 4 sets of brushes in this grinder, I use it day in day out for about 4 hours a day, I thought it would have burnt out months ago but it has a temperature protection circuit that shuts it down to stop it getting burnt out from overheating, best thing ever that was put into a grinder as all the other brands just won't cop hard punishment.
You can buy this brand with confidence, yeah it is double the price of the China junk but you will get more than double your moneys worth at least.

The one thing that sets german made metabo grinders from the rest is the over temp sensor. This shuts the tool down BEFORE the windings of the motor overheat and fail causing a dead motor. (like what happened to my previous 5" grinder) As an added benefit it's got the same body as a 4" grinder and proper variable control that gives full power with any speed. Cheaper grinders work by limiting the voltage to the tool to produce lower speeds and lower torque levels. It also has toolless disk changing, which is worth nothing if you hand tighten the discs (Discs are turning the same way they are tightened, almost impossible for them to come off) If you can stretch the budget for one of these, it may be the last grinder you need to buy.