The first Gretsch badge is their most famous and revered: the Round Badge. It certainly came into use by the 1930s and lasted until 1970. Over those years, the imaging varied slightly on the RB. This is due to the fact that they were produced for Gretsch by at least two different outside sources, accounting for slight variations in tooling. During this period, Gretsch tom-toms had their badges nailed-on with upholstery tacks and even those varied from suppliers. Most snare badges were fitted with 3/8" brass eyelets, and some, like all bass badges, were pressure-fitted with 17/32" nickel-over-brass grommets. Badges for metal snare drums were usually fitted with 3/8" nickel-over-brass eyelets. By 1961, shortly after Gretsch's change from 3 to 6-ply shells, the internal orange/white labels started to appear. Pre-printed with That Great Gretsch Sound slogan, shell guarantee and serial number, the model numbers were usually hand-stamped in indigo or black ink at the factory. Unlike Gretsch's equally-famous guitar line, the drum serial numbers offer little clue to the actual dates of manufacture. However, here is a reasonably reliable dating-system for RB drums by serial number: four or less digits = early-'60s; five digits = mid-'60s, and six digits = late-'60s. (Late-'60s drums usually have internal hex-head shaped screws rather than the earlier round-head style.)