The "key" is a gold medallion wore by members of the Society as an emblem of the Society.
The key is engraved on the obverse with the image of a pointing finger, three stars, and the Greek letters from which the society takes its name. The stars are said today to represent the ambition of young scholars and the three distinguishing principles of the Society: friendship, morality, and learning. On the reverse are found the initials "SP" in script, which stand for the Latin words Societas Philosophiae, or "Philosophical Society". The name of the member and the school and date of initiation is engraved on the key.
Keys may be purchased from the Society's jeweler, Hand and Hammer. Only members of Phi Beta Kappa are permitted to wear the emblem. (Purchase of the key is optional for members, but many desire a visible symbol of their membership.)