[Leica] m grip

[Guy Bennett <guybnt@idt.net>]

i just got a hand-strap for my m6, and am considering a grip. i know leica
makes a grip for the m, but have seen one made by another company (believe
it was made of metal). can any tell me the name of that company, or point
me to their website? also, does any one prefer grip (i.e. the leica one) or
the other?
why or why not? any one dead set against using grips?

thanks, as always.

guy