Aluminum Shifter Knob 3/8"-16 thread - 1-5/8" Dia NEW design for even better heat insulation. Don't burn your hand late in the race! Extra holes are drilled and the ball is mounted with a stainless steel bolt (SS transfers heat poorly). Cooler shifting! NO INSERT to come out; knob won't come off in your hand during the race One piece CNC machined billet aluminum for lightweight. 1-5/8" diameter.