They are a reed organ. I've never played the small hand pumped ones, but my brother-in-law has an older (late 1800's/early 1900's), upright model with foot pumps. It has a sort of eerie Count Dracula-ish sound to it. More of a drone sound than anything else. Definitely a cool instrument. I'd own one if I didn't have to do all that work to actually play it.