SRAM&';s X-Sync 2 tooth profile came out of an intense study of chain and chainring wear - the result lasts longer, runs quieter and holds the chain better than ever. This cold-forged version delivers that same Eagle performance at a lower price than the fully CNC&';d ring, for only about 10g more. Cold-forged aluminum ring X-Sync 2 Eagle tooth profile for 12-speed Eagle chains - superior chain retention and quiet running Direct mount - fits SRAM 8-bolt direct mount cranks Approx. +10g vs. the fully CNC version Choosing the right offset 3mm offset (Boost) - for Boost 148 frames and cranks with a 52mm chainline 6mm offset - for non-Boost (142mm) frames with a 49mm chainline Not sure which you need? Bring your bike to our Midway or Heber City shop and we&';ll match it up.