Oval rings help the rider to spin smoother and more efficiently \n Example: 32t is equivalent to 30t at dead spot and 34t at the power zone \n Narrowwide tooth profile keeps the chain snug, allowing you to leave the chain guide behind \n Fits 104/64 BCD 2X crankset and converts into single ring \n Not Shimano 12 speed compatible \n Designed in UK, manufactured in Poland \n 32t chainring (AI4070 through 4072) has built in 2mm spacers and threaded holes. Use 6mm long minimum bolts to thread directly in to the chainring \n 30t chainring includes (2) M8 T30 aluminum Torx bolts, (2) M5 T25 steel Torx bolts and (2) eccentric spacers to fit 104 BCD spider