StackRight Headset Spacers look great and stay that way! No more misaligned headset spacers thanks to the StackRight technology, which locks spacers together with an interlocking channel for a clean, sleek look. The Essential kit utilizes a standard cap and bolt mounting system for a clean classic look. Fits 1-1/8" threadless fork steerer Inner Diameter: 28.9mm Outer Diameter: 34.4mm Precision-machined 6061 aluminum Kit includes 1.5mm (2), 2.5mm (2), 5mm (1) and 10mm (2) thicknesses Standard headset cap M6 x 35mm stainless steel bolt Specifications: Color: Blue Material: 6061 Aluminum Defined Color: Blue Thickness: 1.5 Thickness: 2.5 Thickness: 5 Thickness: 10 S.H.I.S. Stem Clamp Diameter: 28.6