In Chinese tradition, a silver longevity necklace "locked" a newborn child's spirit to the earth.
Lock charms are Chinese numismatic charms shaped like ancient Chinese security locks. Their shape resembles a basket. The pendants tend to be flat, without any moving parts, or the functionality of the locks they symbolize. They are decorated with both Chinese characters and symbols. Like other types of Chinese numismatic charms, lock charms are meant to protect the wearers from harm, misfortune, and evil spirits, and to bless them with good luck, longevity, and a high rank (through the imperial examination system). In particular, this talisman is meant for the young , to help "lock" them to the earth, to guard them from death.
From the Bea Roberts collection
Pendant is 5" height x 2 5/8" width x 1/4" depth - chain length is 13"