This STANDARD shift knob adapter kit contains 4 different sized adapters and the 4 corresponding jam nuts for use with shift knobs that have a 16mm x 1.50 I.D. thread size. The kit includes 1 each: 1/2 - 20 adapter & jam nut, 3/8 - 16 adapter & jam nut, 3/8 - 24 adapter & jam nut, 5/16 - 18 adapter & jam nut. Adapters are comprised of solid brass. California residents click here for Proposition 65 WARNING label. Made in the USA.