Wurlitzer released the Model 20 in 1946, the year after it acquired the Everett Piano Company’s Orgatron and reed organ technology.

The Model 20 is a keyed reed organ, so the blower only starts vibrating the reed after the key is depressed. Robert Eby has a short description of the Model 20 in Electronic Organs (1958):

It is a two-manual instrument 61-notes each, with a concave and radiating 32-note pedal clavier. It includes crescendo and expression pedals, combination pistons, and provisions for echo organs, chimes and tower amplification. All playing dimensions and console arrangements of the Model 20 conform to the recommendations of the American Guild of Organists.

The Model 21 was produced in the same cabinet as the Model 20. Eby describes the difference:

The Model 21 organ was brought out a short time later and is similar to the Model 20 except that it includes a great to pedal coupler which provides all the stops on the great manual in the pedal section except the 16 ft. pitches and the Celeste 8 ft.

According to Eby, the Model 21 cabinet weighs approximately 740 lbs and is 47 1/2” x 63 3/4” x 33 5/8” (or 47 1/2” deep when measuring to the end of the pedals). The bench is 44 lbs.