Medals featuring the image of St. Michael the Archangel.  These Catholic Medals feature St. Michael the Archangel dong battle with evil spirits.  The Prayer to St. Michael the Archangel explains the image on these medals:

Saint Michael the Archangel, defend us in battle. Be our protection against the wickedness and snares of the devil. May God rebuke him, we humbly pray; and do Thou, O Prince of the Heavenly Host - by the Power of God - cast into hell satan and all the evil spirits, who roam throughout the world seeking the ruin of souls. Amen.