Coleco Perma Power (1982, None, Battery replacement, Model# 2298)
This is Coleco's battery elimination solution. It's basically just a 9-volt AC adapter with 5 different tips. One of them has the same connector as a 9-Volt battery, and that can also plug into one of the C-cell simulators (it comes with 4, one of them with the connector, second one in the picture). These fake batteries can then be inserted into most of Coleco's handheld games if they don't have an actual AC adapter port on them (and any other game that uses 4 C cell batteries). Many of Coleco's handheld games actually have a little hole in the battery cover that will allow the wire from this adapter to easily come out while the cover is in place. It will work on any game that runs on 6-9 volts if you can plug it in. (Center pole positive polarity, non-adjustable).
Here's the Canadian version. Note that the Prototype Donkey Kong Jr is pictured
on the card and the fake batteries are brown instead of black:
Do I have this? Yes, both sealed (US and Canadian), and several loose ones.