The Shimano Deore M5120 rear derailleur can be used with 2x10, 2x11 or 1x10 speed and has the Shadow RD + design, which means that the rear derailleur does not stick out as far to the side as other rear derailleurs do.

It can be used with up to a 46T as the largest gear on the cassette if you drive 1x10.

If you drive 2x10 or 2x11, it can be used with up to 42T as the largest gear.