The Selmer 24A trumpet is a vintage "Balanced Action" instrument first produced by Henri Selmer Paris in the 1930s. It is highly sought after by collectors and jazz musicians due to its unique ergonomic design and rich, sweet sound. Famously played by jazz legends Louis Armstrong and Harry James, its defining feature is the repositioned valve block, which is set farther back towards the bell to create a balanced feel in the player's hands. Key features
 
Unique ergonomic design: The main design feature is the valve cluster, which is positioned closer to the bell, resulting in a distinct "balanced" feel for the player.
Bore size: The Selmer 24A typically features a medium-large bore, with some examples having a .458" bore.
Vintage sound: Many players praise the 24A for its warm, classic sound that is well-suited for jazz, commercial, and even classical music.
Notable users: The 24A was notably used by Louis Armstrong and Harry James, which has added to its legendary status.