Grooved tension band. This piece sits around the banjo head and in conjunction with the hooks/nuts and flange, apply and adjust tension to the head. This banjo is thought to be a 1930s era Slingerland. The Slingerland Musical Instrument Mfg. Co. was based in Chicago, Illinois and was owned and operated by H.H. Slingerland. The company changed names several times, including The Slingerland Banjo Company, Slingerland Banjo and Drum Company and others.