The Rear Derailleur Pulley is made of aluminum alloy, so that it is very firm, lightweight and durable.
Antirust and resistant.
It run on smooth ball bearings, and it's a necessary accessory for your .
There are four different colors for you to choose from, to meet different needs. Hope you will enjoy your cycling. Have a nice day.

Specifications:
Material: Aluminum Alloy
Color: Black, Red, Golden, Silver
Weight: approx. 13g, 16g
Teeth: 11T, 13T (optional)
11T Diameter: approx. 40mm / 1.57
Hole Diameter: approx. 5mm / 0.19
13T Diameter: approx. 49mm / 1.92
Hole Diameter: approx. 5mm / 0.19
Compatible: Suitable for 4/5/6mm spindle shaft rollers

Package Included:
1 x 11T/13T pulley wheel