This is a new old stock Conn 88H trombone, an early Gen 2 instrument made in Eastlake, Ohio, USA. The early Gen 2 Conns with the open wrap F-attachment had a string linkage on the rotor. This one has the later miniball linkage and adjustable thumb paddle. Bell has the early stamp of "88H O/W" meaning "open wrap". The letters "TL" are engraved at the top of the bell stem. Their meaning I know not.
Bell is standard weight rose brass, 8.5", hand spun. Slide action is outstanding.
The only blemish is some small marks under the lacquer of the tuning slide bow. The case latches show some aging from storage.