12" Skull Shifter Shaft Extension Lower Gearshift Cover Skull Biker Knob12" Skull Biker extension kit includes lower shift gearshift knob cover, and 13 15 18 speed skull biker gearshift knob. Ultra high quality finish for durability and shine. 3 4" diameter thick, machined 1 2" 13 male and female threads. Kit includes Highly detailed aluminum skull with helmet and goggles. Fits 13 15 18 speed gear shifter with included adapter. And Lower gearshift plastic cover for Eaton Fuller style 9 10 speed and 13 15 18 speed