Adapter Kit to Allow M16 x 1.5 Shift Knob to Fit Smaller Shifter Stick. This Shift Knob Adaptor Kit from Hurst allows any M16 x 1.5 threaded shift knobs to be converted to fit most standard threaded shifter sticks. The adapter kit includes eight finely machined inserts and matching stainless steel retaining nuts. The eight included inserts are as follows: M16 x 1.5> 1/4-20 M16 x 1.5> 5/16-18 M16 x 1.5> 5/16-24 M16 x 1.5> 3/8-16 M16 x 1.5> 3/8-24 M16 x 1.5> 7/16-14 M16 x 1.5> 1/2-13 M16 x 1.5> 1/2-20