Zhave bought and gotten rid off many accordions in my lifetime; 88 years. I recently bought a Hohner
IV diatonic and like it very much except for the air release button should be up about 3 inches so your thumb, or at least mine, rests on it when your hand is in the normal position to use the cord buttons.There are some accordions that have it up there but not the IV Hohner. I am adding a device of my own design so my thumb will rest on the device which when pushed will activate the air release button. I know there is a proper name for the air release but escapes me at this time. Dan.