SGM Grips Mike is a good guy. SGMGrips.com -
The magazine extension is actually left over parts from my Kimber Ultra mags I filed down one of the mag base plates on the sides to fit the narrower Solo specs, they are almost identical in every other way, I screwed on the extension and you see the result. Fits my hand well, When I carry it, I carry IWB so the grip length is no matter. I have had carpal tunnel surg, my hands are not what they used to be so I appreciate all the grip I can get.
Good luck, what ever you shoot!