Bach Mouthpiece Cases
A good mouthpiece is of such immense value to a brass instrumentalist that he should take every precaution to protect it against loss or damage. It is highly inadvisable to leave the mouthpiece in the instrument or case. The player should have his mouthpiece with him at all times, but if carried loose in the pocket, it is very liable to be scratched, bent, or chocked up. A mouthpiece case is an absolute necessity and you cannot find a better one that that illustrated above.
Source: page 16, Vincent Bach Corporation catalog (1925)
Not 100% sure if this is a Vincent Bach mouthpiece case, but is from a 1927 Vincent Bach trumpet case, accessory, and trumpet collection from J. Landress collection.