via this auction
"One of the rarest electric keyboards out there, the Tubon was manufactured in 1966 by Joh Mustad AB, in Gothenburg, Sweden. Only a small number were produced; fewer still survive.
Imagine a small, strap-on combo organ. The Tubon's sounds are straight out of Sixties organ-driven pop: contrabass, saxophone, electric bass, woodwind. A strong vibrato and adjacent volume control give on-board sound shaping options. Two nine-volt batteries, housed at one end of the tube, provide power. At the other end is a compartment where the strap can be stored.Paul McCartney had a Tubon, though it probably was not used on record. Kraftwerk did use one, along with countless Swedish and Finnish bands...
Output is from a din connector. Included with this Tubon will be a cable with a din plug on one end and a 1/4" plug on the other. You can change the din to a 1/4" female connector if you like; I chose to leave it with the din, to keep it original."
