AEST pulley wheel is equipped with a high quality hybrid ceramic cartridge bearing. The advantages of using a ceramic bearing in the rear derailleur's pulleys are the most dramatic of any other bicycle bearing system. This is due to the high speed at which the pulleys spin; Each pulley is machined from light and strong 7075 aluminum and anodized with laser cut logos. - Brand: AEST - Model: YPU09A-07 - Ceramic bearing feature: High Speed - High rigidity - Long use-life - Low heat - Low heat dilating rate - Corrosion resistance - Non-magnetic - Color: Red - Material: AL7075 CNC processing Ceramic bearing - Functions: Rear Derailleur Pulley Inner diameter: 5mm - Best use: Cycling Mountain biking Road cycling - Packing list: 1 x Rear derailleur pulley