For centuries Mexican mothers have used this bola to help with calming their restless newborns. The harmony bell is worn low across the baby bump so when mum moves the ball rolls and chimes . From 20 weeks in the womb baby is able to hear this sound while they are in this soft, calm environment. After birth mum still wears the necklace so baby can associate the chimes with the comfort of pre birth, so this is how the natural soothing Harmony bell works. a leather chain with silver plated clasp finishes this lovely piece. nickel and lead free , SGS quality certification.