Anyone know anything about Pac Man 2 (Genesis) Lenticular Cover?

Hey There CAG's I have come here for your expert advice today. I picked this copy of Pac Man 2 for the genesis up at a flea market last week. I know they made a cardbox box version and a regular hard plastic case version of the game but I've never seen this lenticular cover before. I tried searching both ebay and google for info on it but came up empty handed. Does anyone know anything about this thing or possibly what it's worth? 

I think mine was like that too!  I got mine on the clearance bin from KB Toys several years ago.  Don't know if it is worth anything though.  Didn't even know if it was released without the special cover.

I have a couple of those.  I don't think they usually sell for any more than the regular ones.