11t pulley set(2pcs) for SHIMANO or CAMPAGNOLO genuine rear derailleur as a replacement. 
Pulley is made of CH10(POM+CF10) that a special plastic includes 10% carbon fiber. It effects durability longer than original ones. Also very quiet.
Shimano Ultegra pulleys wight 22g, CDJ 11t pulleys wight 18g.
 
You can choose bearing type, standard is hybrid ceramic bearings or full ceramic bearings as a option.
 
* This pulley set is not included the derailleur.
* This  pulley set can not be fit to SRAM genuine derailleur.