Zipp's new UD carbon headset spacers allow you to keep your fork secure no matter what you throw at it. 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 your fork secure through every twist, turn and bump in the road.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 your fork secure through every twist, turn and bump in the road.