Different color valves allow you to identify which thickness valve your using The result You can tune your shocks to optimize your cars performance Stack the valves for even more fine tuning Features pre drilled holes which allow you to easily drill them out to custom hole sizes For instance you can drill 3 holes at 1 35mm and the other 3 at 1 50mm Another advantage of the Bypass1 Technology Valve Designation . 003 Green Fast Rebound Valve. 005 Blue Medium Rebound Valve. 007 Clear Slow Rebound Valve. 010 Brown Neutral Valve. 004 Tan Gap Valve Specifications . Size 16 mm