The Enduro line of headset bearings begin with chromium steel, Black Oxide finish A/C type and then offer full 440C stainless steel at the top. They are always engineered with the largest balls possible and dual lip seals riding in a micro groove for ultimate protection against sweat and the elements. They are filled 90% with high pressure water proof grease, so you never have to guess if there is grease inside. Enduro Angular Contact (A/C) bearings, all balls are engaged to spread the force over a larger surface area, decreasing friction and minimizing wear.
There is however one option that exceeds even 440C Stainless steel:
ACB 6808 CC SXD - 1-1/2" Angular Contact Bearing for Internal Headset featuring XD-15 balls and races to provide lifetime corrosion resistance.
This is the last headset bearing you will ever install into your bike.
A recent Enduro development, these full XD-15 bearings are virtually identical in performance and corrosion resistance to our XD-15 Ceramic-hybrid bearings used for hubs and bottom brackets, but lend themselves better to the more abusive application of the headset. The mechanical properties of XD-15 stainless steel balls provide a level of impact resistance superior to ceramic balls for headset application. Enduro testing of bearings with XD-15 balls and races have been run salt water for months without any corrosion, there is simply nothing on the market that compares. We are so confident in this material that we guarantee these full XD-15 headset bearings for life, against corrosion.