STONE 144BCD round Chain ring high stiffness for fixed gearMaterial: Aluminum 7075-T651 from Aleris USAStiffness: 150HBColor: black, anodizedSize: 144BCDArm paw: 5Tooth: 51T to 60TChain compatible:1/2*1/8 inchFit for : Fixed Gear/Track Bike(Single Speed Bike)Thickness:4MMCNC process precision: 0.03mmWe accept customize on tooth quantity. From 51T to 60T.Package Contents:1 x chain ringAdvantages:1 Material: High strength Aluminum 7075-T651, supplied by USA company Aleris who is supplier to aircraft make Airbus, Boeing and Bombardier. Offer best stiffness and endurance.2 High precision CNC processing. Working accuracy 0.03mm. Ensure offers you the best riding component.