The Renthal SR4-4 Arm Chainring is specifically designed to retro-fit to SRAM 2x10 series cranks (X5, X7, X9, X0, XX). The chainring shares the same bullet proof construction of a standard SR4 chainring; full CNC 7075 aluminium with hard anodised finish.  The tooth bed is offset, giving better chainline for improved efficiency and we have threaded the chainring to accept original SRAM chaining bolts. This product was developed alongside the British Olympic MTB squad, who will be competing with this chainring at the London 2012 Olympic Games. Features; Computer aided Ultralite™ design enables the ultimate combination of strength and lightness  High strength 7075-T6 aluminum alloy provides excellent longevity  Precision CNC machined to extremely tight tolerances Hard anodised surface coating for increased longevity Offset tooth profile for improved chainline 8, 9, 10 and 11 speed compatible 120mm BCD (for SRAM 2x10 series cranks) 36T, 37T and 38T available Specifications MaterialCNC 7075 aluminium FittingSram BCD120 Teeth 36, 37 or 38T