The Electro Tone Corporation was a company that produced aftermarket add-ons for Hammond organs in the 1960s and '70s, with more than 2,300 dealers internationally.
The company manufactured the OrganMate reverb kit, PER 200 percussion kit and the Duet Sixteen and Mark II preset kits. These kits were primarily retro-fitted to Hammond organs that required reverb, percussion or presets.
The company was situated at 2014 Broadway, later at 1814-A Colorado Ave, and then at 2126 Pico Blvd, Santa Monica, United States.
References
Electro Tone Corporation Wikipedia(Text) CC BY-SA