The majority of electric die grinders seem to be made to take up to a 1/4" tool. I see Makita make a few die grinders which take up to 8mm, but does anybody make anything larger than this?
These are the heavy duty versions for use with larger tools (polishing tools etc.). The tools (mounted points etc.) over here usually have a 6mm shank, in the US 1/4". I don´t know what you want to do but a grinder with 6mm/ 1/4" collet can do most things...