It's kind of a big deal.
Designed, developed, and produced in Denmark by Ceramic Speed, the Oversized Pulley Wheel (OSPW) System for SRAM Mechanical derailleurs deliver an efficiency-enhancing competitive advantage. With its unique design, the OSPW offers efficiency savings starting at 40% over the stock SRAM derailleur pulley wheels.
This specific version of the OSPW is designed for SRAM's mechanical derailleurs, and as such is only compatible with the following SRAM 10/11-speed derailleurs: Red, Force, Rival, and Apex.
The Ceramic Speed OSPW for SRAM 10/11 speed derailleurs includes two oversized 17-tooth aluminum pulley wheels housed in a robust polyamide and carbon fiber cage, oil, and a Ceramic Speed sticker sheet.