BM540 is designed for heavy off-road and electric power-assisted mountain bikes. It is designed by Koozer in Mainland China and produced in Taiwan, China. It has very fine craftsmanship and higher strength, making it more suitable for AM/FR/DH/E-bike. High-intensity cycling demand.

Please pay special attention to the hub specifications BOOST in this link：20x110 non boost and 20x110 boost, they have the same axle width, but the FIT of the boost version will be 10mm wider, and then the distance from the endcap outside to the brake surface, the boost is 5mm less than the non-boost version, this is very important important important, please confirm clearly before buying.

Important note: for the explanation of common abbreviations, please check the specifications you need before buying. If you are not sure how to choose, please consult our professional salespersons, and we will give you accurate suggestions. We are not responsible for the losses caused by your own purchase mistakes.

28H/32H/36H = the hub has 28 spoke holes/32 spoke holes/36 spoke holes, can fit your 28/32/36 holes rim.

QR = quick release version = front 5x100/rear 5x135mm = front 9x100/rear 10x135mm QR

TA = through axle version = THR = front 15x100/rear 12x142mm

mini THR = mini TA = rear 10x135mm THR or 12x135 THR

Boost = front 15x110mm or 20x110mm / rear 12x148mm

HG/XD/MS = the hub's cassette body is compatible with Shimano MTB 8-11 speed cassette and Sram PG series 8-12 speed cassette(HG) / Sram MTB XG series cassette 11&12 speed(XD) / Shimano MTB micro spline 12 speed cassette(MS).