This is an early Kay double bass, model O100 from 1939 in excellent condition. Serial number is 5597. This Kay bass is in one of the best conditions we have ever seen from an early Kay double bass. Many early Kay basses we have seen have broken or replaced necks, not the case here!!. We recently acquired this bass from the original owner! This kay bass still has the original rosewood fingerboard and nut, as well as the Kluson stamped tuners.