Uncle Mike's. I believe they no longer make grips, but these are fairly common; you should be able to find some on the auction sites or maybe at a gun show.
If you need standard Redhawk grips, be aware that they also made Super Redhawk grips, and the two are NOT interchangeable.
"That means that no matter how we reform health care, we will keep this promise to the American people: If you like your doctor, you will be able to keep your doctor, period. If you like your health care plan, you'll be able to keep your health care plan, period. No one will take it away, no matter what." – President Obama, AMA speech, June 15, 2009.
see 13:20 - 13:58