The crankset features light & strong Hollowtech II technology with 42 Alloy outer ring 32T GF & Steel composite middle ring & steel 24T inner ring The Features of the Shimano SLX 10 Speed Chainset FCM660-10 are:&8226; Dyna-Sys component &8226;42-32-24T &8226; Steel/glassfibre composite middle chain ring for great durability&8226; Cassette Compatibility 10-speed &8226; Chain Compatibility HG-X 10-speed &8226; Crank Arm Length 170 175mm &8226; Bottom Bracket SM-BB70 &8226; Chain Line 50mm