The Wolf Tooth axle uses a captive steel washer under the head to reduce friction on the fork leg. This protects your expensive fork, transfers more of the tightening torque to clamping load for a stiffer interface and prevents the axle from sticking or galling when you want to remove it. These are also a great replacement option for lost or damaged stock axles. Always apply a small amount of grease to the washer and threads when installing.