Martin USA (Holton TR4501) New old stock trombone. This instrument was backstock from a store that has since closed down. Martin TR4501 Urbie Green model jazz trombone. The signature model horn for Urbie Green, this horn is a very hard-to-find model.Trombone itself is in near mint condition, never even taken out of wrapper except for pictures and inspection. Case has some dirt and marks and rust on the latches.