10 Silver Plated Magnetic Clasps Great for Making Necklaces & Bracelets. This is a new set of 10 silver plated magnetic clasps. Great for making necklaces and bracelets. These hold as securely as any normal type of clasp, but make jewelry easier to put on and take off. The magnets are so strong that they should not be used by anyone with a pacemaker. Each measures approximately 15 x 5 mm (9/16" 3/16").