Headset ABEC 3 angular contact ball bearing with 40mm inner & 52mm outer diameter & 7mm thickness and double-lip type sealing with light contact, making a labyrinth seal.

Enduro Bearings don't mess around with inexpensive headset bearings, it's simply not worth it. While many headset makers will offer you Cr-Mo or standard steel headsets for your carbon road bike, steel cross bike, or full suspension mountain bike, they feel that's like putting bias ply tires on a rally car.
Enduro Bearings don't offer the entry level for headset bearings. Instead, they 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 microgroove for ultimate protection against sweat and the elements. They are filled 90% with high-pressure waterproof grease, so you don't have to ever guess if there is grease inside.

Black Oxide bearings which get an additional Fe3O4 Iron Oxide (Magnetite) treatment are corrosion-resistant close to stainless steel but have a better load capacity than this.

In standard radial bearings, only 3 or 4 balls make contact during the load, at any given time. In Angular Contact (A/C) bearings, ALL balls are engaged and spread the force over a larger surface area, to decrease friction and minimize wear.

Features

• ABEC 3 bearings use grade 10 Chromium Steel Balls and 52100 High Carbon Chromium Alloy Races.
• The high precision balls are within 10/1.000.000″ round, twice as round as the industry standard, at its highest level.
• The alloy races are made from a vacuum de-gassed process for the purest chromium alloy steel, hardened to R-62, extremely tough, durable, and polished to a mirror finish for ABEC-3 precision and noiseless movement. The riveted Steel Retainer stands for toughness, ABEC-3 tolerances, and noise tested.