These Enduro ACB (Angular Contact ABEC 5 Bearings) are specifically for bottom brackets that run 24mm bearing on both sides such as Shimano

They are adjustable

the m8100 hub from Shimano lets you run the new 12-speed Shimano cassettes

12mm Bottom

Shimano WH-MT501 12 Speed Micro Spline Rear Wheel - Shimano Micro Spline - 12x148mm Boost - Centrelock - Rear - 29 Inch Heavy/Bulky These Enduro ACB (Angular ContactThe Shimano WH MT501 is a trail ready rim that won't break the bank. Featuring a Microspline freehub body it's all ready for Shimano 12 speed goodness. Who's this item for: Anyone after an entry level complete wheel wanting to run a Shimano 12 speed system. Great for light trail use. Hub: Spoke holes: 24 spokes Convertibility: Not convertible between sizes. Bearings: Cup and cone bearings with contact and labyrinth seals. Brakes: Centrelock rotors