The pack has some type of spill, food, or chemical on it as shown. I don’t know if it affects the cards. Though I found packs like these on eBay, I didn’t find any with McGwire on top and Clark on the back.

Sealed 1990 Post Cereal Baseball Card Pack Mark McGwire (Top) Will Clark (Back). Condition is "Acceptable". Shipped with USPS First Class.

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