"Gold filled" medals such as this St. Christopher have thick, mechanically applied gold at least 10Kt.,which weighs at least 1/20Th. of the total weight. This nice oval piece measures 11/16" x 1 1/16" and has a 24" chain.
St. Christopher was a 3rd century man who made his living carrying people across the river. One day Our Lord, as a child, was his passenger. Hence, this saint is the patron of travelers.