CeramicSpeed Ceramic Oversized Pulley Wheel Black Sram eTap.

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

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

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

For Srams eTap rear derailleurs.

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

Made of aluminum and with ceramic bearings.

607 bearings.