This adapter is convenient when the diameter of your shift knob changes, such as when switching vehicles. You can install a shift knob with a size of 12 x 1.25mm even if the diameter and screw pitch size of your car's shift knob lever is 8 x 1.25mm. (However, the lever will be about 2mm longer.) Material: Aluminum alloy Total length: 14-15mm Shipping will be by non-standard mail, but shipping is free.