This is a mellophone. It is left belled, with pistons instead of rotors. It is a bit smaller than a French Horn also. It has long been my understanding that no manufacturer still offered these for sale new, but in the early 1900's you could get them from all the big companies like Conn, Wurlitzer, King, Olds. Today, you can buy them used, a dime a dozen, on EBAY.COM.