Sram Black Box Ceramic Bearing Jockey Wheels XX1 & X0 11T Headsets and you'll find some interesting

and you'll find some interesting structures

41mm Upper Cartridge Bearing 1 1/8”

breathable fabric and flatlock seams for comfort

Brake Type: Hydraulic

1-Freewheel turner for 5 to 10 speed cassettes and freewheels

Sram Black Box Ceramic Bearing Jockey Wheels XX1 & X0 11T Headsets and you'll find some interestingSram Black Box Ceramic Bearing Jockey Wheels XX1 & X0 11T The SRAM Black Box ceramic derailleur pulleys are made of the same material as the standard pulleys, but they use polished stainless steel races and ceramic ball bearings in a sealed unit. The pulleys are a bit lighter and more durable thanks to the ceramic balls, but more importantly they have substantially less drag than standard stainless steel balls. And they can be taken out and re lubed