The Box One Cassette Spacer Kit is extruded and CNC-machined from 6061-T6 aluminum and features a super lightweight minimalist design. Packaged in 4-piece kits which provide 1 to 10 millimeters of spacing adjustment to dial in that chain line. FEATURES - Adjustable from 1mm to 10mm for Adjusting Chainline - Extremely Lightweight XO Skeleton Design SPECIFICATIONS - Material: 6061-T6 Aluminum - Extruded & CNC Machined - Anodized Finish - Spacing: 1-10mm (1mm [2], 3mm [1], 5mm [1]) - Driver: HG Freehub Body