The screw has 1/4""-2 threads which are very common. These will fit the threads that hold the air cleaner on older cars that aren't metric. (great for rat rods)

• Beautiful black chrome spike is 2 3/4"" long.
• Base of the spike is 3/4"" dia.
• Made from solid aluminum, has a quality finish unlike the cheaper spikes available elsewhere.
• Common 1/4""-2 threads.