The cornet with the vertical tuning slide known as the 80A is a pretty common cornet. The 80A with the linkage started as early as 1914 down to 1940. It was a #2 bore as opposed to a # 2 1/2 bore. As I recall, the #2 bore is a. 468 and 2.5 bore was. 484 It was slightly longer as well as narrower.