Renthal R3 O-ring chain, a high quality o-ring chain. A 520 o-ring chain designed for the extreme rigours of off road use.  Nitrile ?O? Rings extend chain life by retaining special  vacuum injected grease inside the chain joint.  Shot-peened alloy steel side plates for high tensile  strength and maximum impact load resistance  High carbon alloy steel bearing pins for excellent  resistance to wear.   Gold coloured side plates help prevent corrosion.  Pre stretched to enhance performance of the chain.