This is the best track cog money can buy. Made by Euro Asia Imports for professional track use - they have perfect threads, roundness and precise tooth profiles for the smoothest possible drivetrain ride quality. The golden titanium-nitride coating increases strength, durability and lubrication. If cared for properly, these cogs last virtually forever! Check out the pros bikes on the World Cup and Olympics at Beijing and this is the cog you will see threaded on most wheels. Combine with an Izumi V chain and a high quality chainring(Dura-Ace or Sugino Zen) to optimize the Gold Medal cog's performance. Available in 1/8" pitch only. Limited supply.