CeramicSpeed Ceramic Oversized Pulley Wheel Red Shimano?.

CeramicSpeed makes some of the strongest, most accurate and lightest rolling bearings on the market, which are all ceramic.

Ceramic bearings also provide better utilization of one's wattage.

Oversized Pulley wheels are, as the hub suggests, pulley wheels that are larger than normal, this gives less movement in the chain, which therefore gives less energy loss and ultimately a greater power transfer.

For Shimano's 10 and 11 speed rear derailleurs (Only Ultegra and Dura Ace, but not suitable for 9100).

Comes with a new rear derailleur arm so you can change the whole set that way.

Made of aluminum and with ceramic bearings.

607 tenants.