RaceFace Next SL 10-11 Speed 175 Crank Arms with 170 Rears The crank arms are completely hollow with all unnecessary material being removed from the centre core - no internal aluminum spine Industry standard 30mm spline interface CNC machined from an aluminum that is 20% stronger than 7050 alloy (commonly used in this application) Removable spider (sold separately) offers the ability to convert between existing chain ring standards while remaining flexible to future developments Weight: 535g (22/36T, 24/36T), 540g (24/38T) Direct mount single chain ring option (sold separately)