Built-in 10mm reinforced magnet, sure to hold more metal ball marker and have them in place. Made of high quality alloy, nickel plated, silver in color; durable and corrosion resistant (Would rust after long used even nickle plated. Please put it off your hat while not on court.) 25mm (1") flat disc plate is for ball markers in most sizes like 1.25". Easily clip to your golf gloves, bags, hats, visors, belts, shorts, trousers, shirts, pockets; for super quick access to your ball markers on court.