An All National Guard Shooting Team member out of California was involved in the development and manufacture of these things. Last time I saw him, almost 30 years ago, he was an Air National Guard Captain. First name was Gary. Had an odd last name spelled something like Gooregian. Nice well engineered mounts. You bought the grip either for a low mount (no rib) or a high mount (Bomar rib) and then bought the base for what ever sighting system you planned to use. I've got one in the shop. My new Baer 45 will become a wadcutter gun and wear it. Pictures say it all. You will see it again with a Burris Gil Hebard 2X scope in Burris Z rings when I post pics of the gun.