I'm hoping to find some type of chart that explains the expiration codes on the Button Cell Watch Battery Blister Packs used by Energizer and some of the foreign(?) suppliers like Blue Dot Trading, Eunicell etc. From contacting an Energizer Company CS rep, I found that MC means they expired in Dec 2019. But, I'd rather not spend 20 minutes on the phone every time I need to know. Some of the sellers on ebay either do not know these codes or they're selling expired batteries intentionally.