Tiger, the name on the side there, is the company that made these and many other games. Try looking for information on Tiger Electronics product lineups from the 1990s. They had a few MK franchise items back in the day.

I had a Tiger electronic handheld MK1 game, was pretty decent for the medium. Had special moves too.

Ka-Tra

Thank you. I was able to find out the Tiger made these but you really dont see them at all or that I am aware of. Nothing on Ebay, couple of vidoes on youtube of 1994 but that is it. Nothing else other than a few pictures I found on Google. I bought it from a guy that was selling me a 1980s Star Wars snow speeder and he threw the rockem sockem in for a total of $50. It all works, has sounds and the screen keeps track. Mortal Kombat is the only game I really play, specially back in the days when I had my old Sega system. the first game.