Tough enough for Enduro, Downhill, and also weight conscious for XC riding, Praxis MTN Wave™ rings are machined from 7075 T6 aluminium and hard anodized to take a beating. Licensed and developed in conjunction with Mountain Racing Products, the Wave™ pattern tooth profile applies alternating lateral force to each chain link to actively retain the chain to the ring – going beyond narrow/wide implementations that rely solely on friction, while allowing room for mud, debris, and grit to escape. The Wave™ design also wears more slowly than competing designs by spreading the load over larger surface areas.PLEASE NOTE: Chainring bolts are NOT included.• Installs on 4-arm 104BCD MTB Crank.• RD- Must use ‘CLUTCH’ type rear derailleur. Example Shimano Shadow or SRAM Type 2.• In very rough terrain, or just for pure security, we still recommend use of an upper guide.Specification:• 104 BCD | 30t - 36t | 7075-T6• Wave™ Tech tooth profile• 10/11/12sp Shimano/KMC/SRAM• Stamped and machined manufacturing with hard black anodizing for durability• REAR DER- Must use a ‘CLUTCH’ type rear derailleur. Example Shimano Shadow or SRAM Type 2• In very rough terrain, or just for pure security, we still recommend use of an upper guide