Up for sale is an Epiphone bass IV bolt-on neck. Looks like a Thunderbird. See photos. It was declared a factory blem with USED stamped on the headstock and part of the serial number removed. This indicates a defect of some kind. Cosmetically, light nicks and scuffs. Functionally, the truss rod turns fine but the neck has a significant back bow no matter what position. It will need work. It does reduce when slackened.