There were numerous models of Frank Holton & Co. trombones through the years. This is a collection of user submitted instruments. Click on thumbnails for larger images.
Here’s what a Holton catalog circa 1920s had to say about this horn:
The Holton Special has been in use by prominent trombonists for almost a quarter of a century, and has won its way to the top on its merits alone…Superior metal and skilled tempering, combined with perfect graduating of the metal and scientific proportions of the bell and tubing, have made the Holton Special, with the exception of the Revelation Model, the most perfect trombone manufactured.”
It has a 7-inch bell which indicates that it is medium bore according to a period Holton catalog. The hand slide has “Pat.10-27-08 / Frank Holton / Chicago / 0 / >3<” stamped on the hand slide.
Gold wash 7 in bell
Revelation in-slide tuning