Problem Solvers Locking Headset spacers help maintain headset adjustment when removing or replacing stems and have a compact, lightweight, and unobtrusive design.Maintain headset adjustment when removing or replacing stemsCNC-machined AL-6061-T6; compact, lightweight, unobtrusive design8mm stack height, 34.5mm OD to match diameter of most aluminum stack spacers4mm stainless steel bolt; requires 3mm hex key for installationItem SpecificationsColorSilverUnit of SaleEachMaterialAluminumThickness8mmS.H.I.S. Clamp Diameter28.6