XX1 JOCKEY PULLEYS
SRAM's XX1 introduced more than just wide/narrow chainrings. The pulley wheels on their X-Horizon rear derailleur followed the pattern with 12-tooth narrow wide cuts. Absolute Black's new upgrade kit uses full Delrin wheels with alloy outer plates and stainless steel bearings. They say they're long wearing and quieter than alloy pulleys, but they're only made to fit the SRAM X-Horizon rear mechs (XX1, X01, and presumably CX1).