Zipp Headset Carbon Spacer Set 1-1" diameter in 4 (x2), 8, 12, and 30 mm heights UD carbon fiber finish Defined Color: Black S.H.I.S. Stem Clamp Diameter: 28.6 Imprecise spacers can cause your headset to loosen, affecting bike handling and component life. Lightweight and precisely parallel, Zipp carbon headset spacers are precision ground to keep y