SRAM XX1 Eagle Copper 12 Speed Chain 126 links

Your high end chain upgrade if you are coming from NX, GX, or even X01.  XX1 chains are lighter, stronger, and have the longest wear life compared to lesser SRAM chains.  Not cheap, but at least they have a long lasting track record. 

The SRAM XX1 Eagle AXS 12-speed chain is a high-performance lightweight chain that features a unique design for significantly improved wear resistance on Eagle cassettes and rings.

• Eagle chain links have a smooth radius, with no sharp edges or chamfers which yields a significant reduction in noise, friction and wear
• PowerLock chain connector features Flowlink technology to provide superior chain-guiding and increased longevity
• Hollow pins feature a hardened chrome treatment for long-term durability