Trek lower headset bearing, 440C stainless steel used in 2010 and later model Madone frames as well as some Domane frames. Also used in Crockett and Cronus frames in the lower end of the head tube.

Our part number: ACB6808SS

Replaces Trek part number 290413 and 417578

Dimensions: 40mm ID x51mm OD x 6.5mm Wide. 36-degree x 36-degree design.