Similar to the 2600 Kid's Controller, Atari Gaming Headquarters owns the only one prototype of this peripheral is known to exist. It was shown to the public for the first time at World of Atari '98 in Las Vegas. Astro Grover and Big Bird's Hide & Seek were but two of the planned titles for this device.
Because the 5200 SuperSystem was a comparatively expensive machine in its day, there really wasn't a market for a special controller for kids since the machine itself generally catered to the hard core or adult game player. By 1982, the bargain-priced 2600 system was the choice for people looking for starter systems, and it also served as "hand-me-downs" to many youngsters as well. Which is why we saw a 2600 Kids Controller come to market but not one for the 5200.