The ceramic bearings&#39; performances are very nice, especially in the low load and high-speed environment. This guide wheel will optimize your speed rear derailleur with reduced friction and extended lifetime.<br/>Features:<br />Compatible with most rear derailleur on the market, supporting 11T / 13T, 4 / 5 / 6mm shaft guide wheel screw.<br />Guide wheel selection: please try to select the same as the origin-al guide wheel, and if not, you can choose a smaller one than the origin-al one.<br />Suitable for most cycling applications, whether it is road, MTB, or triathlon, these pulley wheel will optimize your speed rear derailleur with reduced friction and extended lifetime.<br />Lightweight design, these lightweight pulley wheel are fitted with ceramic bearings, which reduce friction and feature increased lifetime.<br />The aluminum alloy is very practical, and together with the pulley design, the set optimizes the overall performance of your derailleur.<br />It is easy to install and can be used as a nice repairs or replacement part of the bicycle to increase the service life of the bicycle.<br/>Specifications:<br />Material: aluminum alloy&#43;ceramics<br />Specification: 11T , 13T (optional)<br />Application: 4 / 5 / 6mm shaft guide wheel screw<br />Item diameter: <br />11T: 41mm / 1.6in<br />13T: 49mm / 1.9in<br />Item weight: <br />11T: 9g / 0.32ounce<br />13T: 11g / 0.39ounce<br />Package size: 150 * 100 * 30mm / 5.9 * 3.9 * 1.2in<br />Package weight: 15g / 0.53ounce<br/>Packing List:<br />1 * Rear Guide Wheel<br/>