ZERØ Ceramic Pulleys for Shimano 11-speed derailleurs.

Independently tested and winning competitions for the least rolling resistance, the truly best part of these jockey wheels is the silent and crisp shifting they afford. Machined from solid Delrin at Enduros California machine shop, not molded, they are much harder and precise than any competitor′s that have copied this design. Where aluminum jockey wheels are loud and deteriorate almost immediately after installing, Enduro Bearings jockey wheels will shift perfectly and precisely a year or two from now just the same as the day you installed them.

Proven time and again in World Cup race conditions, the ZERØ Ceramic pulley bearings are the ultimate race day weapon. Oversized Grade 3 balls roll on races which are ground to a mirror finish after receiving Magnetite and then Cryogenic treatments for hardness and longevity. More durable and with even lower rolling resistance than any 2RS bearings, they come closer to that magic “zero” rolling resistance number. Enduro Bearings uses Silicone seals which are more slippery than rubber seals used by other ceramic bearing suppliers. They get more email and blog feedback on the ZERØ′s than any other bearing, describing the noticed difference in downhill rolling speed. And they win the independent wattage output tests when stacked against the competition.
If you want to buy raw speed, ZERØ Ceramic bearings are it.