N.M.S. Co. Black Diamond String Store Display. Store counter top display cabinet for The National Musical String Co. “Black Diamond” strings with painted advertising boxes on the front for Guitar Bronze Wound Strings, Banjo Silver Plated Strings & Mandolin Monel Wound Strings, display glass on the front exposes 8 rows in 4 columns of strings with original paper label on the rear sliding door identifies the cabinets contents including Giutar, Banjo, Mandolin, Haw-Guitar & Violin strings. Tin cabinet has its original painted surface with some light surface rusting, in excellent overall condition. 17.25 in. high x 19.25 in. wide x 10 in. deep.