Product Name: STONE 76 BCD Chainring, narrow wide Material: High strength Aluminum 7075-T651, supplied by USA company Aleris who is supplier to aircraft make Airbus, Boeing and Bombardier. Material Hardness:HB150 Color: black Size: 76 BCD Thickness: 4MM Speed: 9/10/11 speed Fit for Sram XX1 Surface treatment: Anodize, high speed CNC 32t-36t is Non-Hollow style 38t-42t is Hollow Style Features: Stone workshop new design narrow wide tooth, enhanced anti chain drop, enhanced self clean from soil dirty and less noise. Tooth Max diameter(mm) Weight(g) 32 T , 134 mm , 44 g 34 T , 145 mm , 51 g 36 T , 154 mm , 62 g 38 T , 162 mm , 74 g 40 T , 170 mm , 85 g Package: 1 chainring, 4 bolts Advantages: 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 Most Stone chainrings produce by order, it need several days to produce. Hope you would understand 3-5days prepare time.