The brass circles were marks of Washburn's "higher" quality instruments. Look at the A series guitars: A-5 is bolt on, plastic dots..... A-10 is set neck, plastic dots, 2 dbl pups, 4 pots and toggle..... A-15 is set-neck, strat pups, plastic dots, 3 pots and slide switch.... A-20 is neck-thru, brass circles, 2 dbl pups, 4 pots and toggle. (all came with whammy config if desired--"V" models of each). So gradating upward to the brass circles. Look at the B-20 Stage basses, unusual shape meant to stand out, superb "extra" craftsmanship, brass circles, neck-thru (the only stepped neck-thru I know of in our vintage basses--as a tribute to our pal, SP_EB4L!! ) It is a pièce de résistance for them in 1980 when it arrived on the scene. The lower cost B-5: bolt-on, plastic dots. Ravens--plastic + Hawks---plastic vs Falcons---available in both plastic or brass circles + Eagles---brass circles Brass rings says "Look at this! It is our best stuff!" That's how I read it. I have had girlfriends who said my you-know-what should have brass circles. So I peeled off the plastic dots. It hurt. Never again (the heck with depth gauges) and I sure ain't gonna de-fret it.