Sterling Silver Ideal for those who have difficulty using regular clasps A spring ring is fixed to attach to an existing clasp Complements a variety of necklace and bracelet designs This Sterling Silver barrel-shaped magnetic ball clasp converter fastens via a magnet in each hemisphere of the clasp. Perfect to use with a variety of necklace and bracelet designs and interchangeable jewellery, the clasp provides a secure hold, yet opens and closes easily. This makes it ideal for those who have difficulty using regular clasps. Attach the spring ring to the ring end of an existing clasp, and for the opposite side, attach the hook/closure side of existing clasp to the ring of this magnetic clasp. The clasp measures 4.5mm in diameter and the spring ring measures 5mm.