THIS key comes with total 5 prongs (EVEN Numbers), so this is best item as master key for all your clock. If you owe many winding clock in your stock but always problem for the key. Most of all winding clock keys available in these 5 prongs. Some extra larges key holes are not available in these keys. EVEN Sizes: 2.75mm 7/64 in (2), 3.25mm 1/8 in (4),3.75mm 5/16 in (6), 4.25mm 11/64 in (8), 4.75mm 3/16 in (10). - This key is Made of BRASS