Product Name: STONE 130 BCD oval Chainring, narrow and 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 CNC process precision:0.03mm Color: black/sliver Model:hollow and aero Size: 130 BCD Ovality: 8.3% Thickness: 4MM Speed: 9/10/11 /12speed Support both Sram and Shimano 12 speed chain Fit for: 130 bcd crank for Sram red for Rotor for Shimano 5700 6700 for Brompton for 3sixty Surface treatment: Anodize, high speed CNC Process pricision: 0.03mm Package Contents: 1 x chainring, 5 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. Tooth Max diameter(mm) Weight(g) 40 T , 178 mm , 86 g 42 T , 186 mm , 85 g 44 T , 194 mm , 90 g 46 T , 202 mm , 86 g 48 T , 210 mm , 99 g 50 T , 219 mm , 107 g 52 T , 226 mm , 112 g 54 T , 235 mm , 119 g 56 T , 242 mm , 124 g 58 T , 250 mm , 129 g 60 T , 259 mm , 133 g Most Stone chainrings produce by order, it need several days to produce. Hope you would understand 3-5days prepare time.