The new Shimano XTR, XT, and SLX 12spd Hyperglide+ chain works differently than other products on the market so Wolf Tooth engineers developed a completely new tooth profile to provide optimal chain retention and durability when using this new chain technology. Fits any 104 BCD crankset The new HG+ chain interacts with the chainring much differently than a traditional wide/narrow design. Wolf Tooth engineers spent the time to understand how the system works and design a new tooth profile that is optimized for this system. Engineered proprietary tooth profile maintains the quiet and smooth performance of the HG+ drivetrain with legendary Wolf Tooth chain retention. Prevents premature ring and chain wear that can come from non-optimized profiles. Compatibility Fits any 104 BCD crankset Compatible with Shimano 12-speed Hyperglide+ chains Chainring Bolts: All tooth sizes require 1x bolts that are 6mm long with exception to 30t rings which are threaded and require bolts that are 7-10mm long. Wolf Tooth carries both sizes in a variety of colors 104 x 30t - use 10mm bolts 104 x 32t, 34t, 36t, 38t use 6mm bolts. If using a bashring you will need 8mm bolts (most stock bolts on 3x cranksets are 8mm) 104 BCD chainrings work on many older 2x Shimano crankset (XT, SLX, or Deore)