I have a Volquartsen 1 piece grip with Thumb rest for Ruger MK1/Mk2 was put on the gun for a bit but never fired put back in the pkg after having it on . only selling because I just didn't seem to like a thumb grip but that's me and my personal pref.
Asking $40 Shipped OBO
here's the discription of them from the Brownells web siteBrownells
Large, contoured, bottom-swell heelrest and wide, upswept thumb-rest straighten and extend the wrist for a relaxed, steadier hold and more reliable accuracy. Wedge-shaped grip area (wide in the rear, narrow in front) and evenly spaced finger grooves match the natural shape of the hand. Secure one- or two-hand hold. Available for Ruger Mark II, pistols.