The new Dirt Tricks Zirconium Rear Sprockets are 2oz lighter than our chrome plated design, and are comparable to most of the performance aluminum sprockets and lighter than the twin metal designs available. The new coating on these sprockets reduces friction up to 50%, increases durability, and looks sharp! Our Special Edition sprockets will outlast any sprocket on the market, and we back that up with our 2 year guarantee. Proudly made in the USA.