BOX COMPONENTS Zero Shimano Compatible BMX Bicycle Hub Spacer Kit - BX-HU130SHCS Extruded and CNC-machined from 6061-T6 aluminum feature a minimalist design that is super lightweight and extremely good looking Sold in packs of four, including two 1-millimeter and one each 3- and 5-millimeter widths set provides spacing adjustments from 1 to 10 millimeters