1、Anodised CNC machined, bicycle derailleur pulley with fully sealed bearing for center bolt derailleurs. 2、This sealed jockey wheel can not only effectively reduce the resistance when riding, but also improve the efficiency of riding, which allow you to enjoy the riding process more comfortably. 3、This jockey wheel is made of CNC aluminum alloy, which is lightweight and has good rust resistance. 4、This bike jockey wheel is very convenient to install and disassemble, which is suitable for the old derailleur, and 4, 5, 6mm spindle rollers. 5、Our rear derailleur guide wheel is lightweight and will not put extra burden on your bike. This bike jockey wheel is mainly used to protect the center bolt derailleur of the bicycle, so that the pulley runs on smooth ball bearings, thereby effectively extending the service life. Features: Anodised CNC machined, bicycle derailleur pulley with fully sealed bearing for center bolt derailleurs. This sealed jockey wheel can not only effectively reduce the resistance when riding, but also improve the efficiency of riding, which allow you to enjoy the riding process more comfortably. This jockey wheel is made of CNC aluminum alloy, which is lightweight and has good rust resistance. This bike jockey wheel is very convenient to install and disassemble, which is suitable for the old derailleur, and 4, 5, 6mm spindle rollers. Our rear derailleur guide wheel is lightweight and will not put extra burden on your bike. Specifications: Material: Aluminum alloy, steel Model: 11T/ 13T (optional) Color: Black/ Colorful/ Red (optional) Size: 5.1*5.1cm/ 2*2in Weight: 13.7g/ 0.5oz Package list: 1 * jockey wheel 1 * jockey wheel