RickAnderson
Custom
There may be more to that. Come to think of it, it was only after the design became public domain, did AR-15 sales explode. Before that, only Colt sold them and they didn't market them to much, sure a few adds here and there, and IIRC, they were expensive....Well it too a few years to catch on in the market. But when it did - whew!
Suddenly anyone could build and sell one, and they were off to the races...