Shimano SLX M7100 10-45t Cassette.

The 10-45t gearbox gives less gap between the gears and thus gives a better flow in the lighter gears.

Since it is the lightest gear with 45t, it is good for flatter conditions like in Denmark.

The largest gear is made of aluminum to keep the weight down, and the smaller gears are made of steel, to be able to withstand the wear and tear from the several times they run around.

The teeth are made with Shimano's Hyperglide+ technology so it shifts better, and it is quieter when you use Shimano's chains.

It mounts on a Microspline cassette case, so you can't mount it on a regular cassette case.

With the new system, it also runs with a 10-tooth cog as the heaviest gear, so the cassette spread is wider, giving you a higher top speed

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10-12-14-16-18-21-24-28-32-36-40-45T

If you run 2x12s, this cassette is also the one you should use.