This keychain has a stainless steel laser engraved charm with “Have a piece of Pi” with the Greek letter Pi on it. The pendant measures approx. 3/4 inch across. This item is a multi-purpose convertible piece and the pendant piece of this keychain can be "un-clipped" to wear on a chain or necklace if desired. This item contains small pieces and is not intended for children under the age of 14.