Trek Session Headset Bearing Kit - FSA/ Standard Options 2011 They are always engineered with

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

It actually cleans your chain as you ride

(for hubs with axle stops)

The kit contains two bearings of the one size

RATCHET TOOL MATERIAL: Chrome vanadium steel

Trek Session Headset Bearing Kit - FSA/ Standard Options 2011 They are always engineered withTrek Session Headset Bearing Kit FSA Standard Options This Headset Bearing Kit fits all Trek Session models. The kit contains two bearings of two different sizes in the following options. FSA (Full Speed Ahead) Kit (The OG Bearings used by Trek) FSA headset bearings are high quality, precision engineered components designed to deliver smooth steering and long lasting performance for both road and mountain bikes. These Angular Contact Bearings (ACB)