Please be aware that this sprocket bolt set comes with a countersunk head (exactly as shown in the image). Some sprockets do not have countersunk bolt holes. Please check your rear sprocket is compatible with this style of bolt before purchasing. *** New set of 6 High Strength Sprocket Bolts and nylon locking flange nuts. These are factory recommended 10.9 grade, Chrome, anticorrosion barrier , . The size is M8x30 and is correct for most bikes. They are strong and designed to be tightened with a larger 8mm Allen wrench and 12mm wrench. Please be aware these bolts do not work with the 950/990 rear sprockets