Sickspeed Shift Knob Adaptor Standard Thread Kit Set For 1/2-20 3/8-16 3/8-24 for Acura CL Fits Sickspeed shift knobs. These jam nut and reducer is for all of our standard thread pitches Comes with 3 separate jam nuts and reducers. 1/2x20, 3/8x16, 3/8x24 . Installs in seconds!.