This is a rare Conn 7H trombone from the USA Artist Series, featuring an 8 5/8-inch bell and a .525 bore with a small shank receiver. I purchased this instrument used in 2018 and didn't receive much information from the previous owner, so I assume it had been sitting in a case for a long time.
This trombone has a beautiful sound and was my go-to instrument for playing classical and early Romantic orchestra parts, as well as for big band, commercial work, and my own projects.