Those came out only for a short time about 15 years ago....I forget who was making them.
They are hooked up to one lamp on the bill acceptor bezels' dual lamps.
When the power comes on the bezel, the unit is turned on and the sticker begins to flash across.
There's a long ribbon cable that runs back to a power supply brick and circuit board.
Those were the coolest things to have!...I remember buying half a dozen of them....haha
It's possible some folks may still have one or two laying around collecting dust.
There used to be some blue ones too, as well as the black and yellow ones.
I know an NLG member was selling some last year.