Extruded and CNC-machined from 6061-T6 aluminum, Box Two™ Stem Spacer Kits feature a lightweight design. Weights range from 0.24 to 0.29 ounces (6.7 to 8.2 grams), depending on the size. Sold in packs of five, each set provides spacing adjustments from 1 to 20 millimeters.