Some games are released both with and without slip covers. For example, I ordered Deus Ex: Human Revolution from amazon and it came with a slip cover, but I just seen it sitting on a store shelf being sold without the cover. For some older games it might be hard to know if a game was released both with and without a slip cover. How should we handle this? Separate entries? A check box under the barcode in the game description indicating that there is a slip cover, but maybe not for each release? Something else?