The instrument was custom-built at the request of Tanner, who appreciated the Theremin sound but wanted greater control of note pitch and attack. It featured a long slide bar controlling pitch, and a knob for controlling amplitude. The Electro-Theremin was never mass-produced or sold, and Tanner's prototype may have been the only one in existence.
Tanner played the instrument on a number of television and movie soundtracks, an LP entitled Music from Outer Space. Most famously, Tanner played his Electro-Theremin on three tracks by The Beach Boys, including "Good Vibrations". He sold his only Electro-Theremin in the 1960s, as he felt that modern synthesizers were making it obsolete.
In 1999, a man named Tom Polk reconstructed a version of the Electro-Theremin and named it the Polk-Tannerin.