120 BCD cranksets were introduced with 2x10 drivetrains a few years back. These rings will allow you to convert your 120 BCD crankset, like the SRAM XX, to a 1x application.
For SRAM cranksets: You must use the stock M10 bolts. These are not standard bolts and Wolf Tooth's bolts will not work with this chainring. Note that only about 3 threads will engage (same with the stock SRAM rings)
For non-SRAM cranksets: You will need the M10 bolts from Wickwerks if your crankset doesn't already have them. These bolts actually have more threads engaged and will work better than the SRAM ones.
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