Stroke: High strength material - high strength hot forged alloy steel, spindle head rivet head is durable and rust proof Marked sturdy housing - comes with a colorful sturdy plastic housing for storing and classifying different spindle sizes Available sizes - metric M3, M4, M5, M6, M8, M10 and M12 all 7 sizes are available Save money - save money by replacing rivet nut spindles instead of buying new rivets Universal mounting - suitable for many standard nut rivets Specifications: Size: m3/m4/m5/m6/m8/m10/m12 (optional) Material: steel alloy Quantity: 1 package Storage: color label plastic shell Packing list: 1 * M4 spindle 1 * Storage box