On the HSK 7-9 vocabulary list, at CEFR level C2.

méi ㄇㄟˊ

    • classifier for small objects: coins, badges, rings, carved seals, chess pieces, eggs, fingerprints etc (more formal than 個|个[ge4])
    • classifier for bombs, missiles, satellites etc
    • classifier for flat items (from Japanese 枚 "mai")

      on product packaging

    • stick used as a gag to prevent soldiers from talking while sneaking up on the enemy

      old

Sources