What's in the box:

Bicycle Guide Wheel 12T Tooth Ceramic Bearing Mountain Road Vehicle Aluminum Alloy Rear Steering Wheel Bicycle Rear Derailleur Narrow Wide Ceramic Bearing (Gold)

The ceramic bearings' performances are very nice, especially in the low load and high-speed environment. Compatible with most rear derailleur on the market, these pulley wheel will optimize your speed rear derailleur with reduced friction and extended lifetime.

Features:
Compatible with most rear derailleur on the market, supporting 9 / 10 / 11 speed.
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.
Lightweight design, these lightweight pulley wheel are fitted with ceramic bearings, which reduce friction and feature increased lifetime.
The aluminum alloy is very practical, and together with the pulley design, the set optimizes the overall performance of your derailleur.
The removable design also makes the maintenance much easier.

Specifications:
Material: aluminum alloy+ceramics
Color: black, red, blue, gold (optional)
Specification: 12T
Item size: 50mm / 2.0in
Item weight: 12g / 0.4ounce
Package size: 100 * 50 * 50mm / 3.9 * 2.0 * 2.0in
Package weight: 19g / 0.7ounce

Packing List:
1 * Bicycle Rear Derailleur