Not a Bomar or LPA as rumored, nor a Proprietary...

It is a Kimber Adjustable cut used on Kimber full size target 1911s. Dawsons for Kimber Adjustable fit properly (drift with minimal effort, plastic drift), screws lock in proper spots, perfect....

I wanted Fiber Optics (old eyes) and bought and sold several until I found a fit...

Interesting. When I went looking for a replacement grip safety for my Nightmare, I was told that a Kimber unit would be a drop-in fit. And it was, looks like it was blended to the frame without any additional work on my part.