That is what I bought at an Army/Navy store to hold my pinpointer, pouch and digger. You can still get them today. When I was in the USAF in very early 80's, our fatigue uniform belts were still like that including the buckle. Dress uniform buckles were different.
This is a present day USMC BDU buckle, these are awarded by your ability to perform in martial arts, top belt is black. I bought this at a small convenience PX. Oh how times have changed.
I want to add that all buckles are black, all Marines are issued a tan belt then work their way up, pictured is a gray belt. For the record I was in the Army 11-B-10 Infantry 74-75.