Praxis Works Doon CranksPro level carbon arms with M30 Thru (30mm) alloy spindle Cold forged, proprietary LevaTime II X rings (104 160BCD) with steel chainring bolts *M30 Thru BB sold separately, use PX9019 for English 68 73mm, PX9023 for BB30 PF30 or PX9022 for BB86 and PX9024 for T47 external BB tool sold separately, use PX8980 8981 Direct Mount 3 bolt for 1x chainring conversion is possible For additional Praxis 2x chainring options, use PX211* Works with 10 11 12sp