Check the model number of your Hubsan!
107L, 107P -> 0720 motors
107C, 107D -> 0820 motors
Please note that the Hubsan X4 107P and 107D+ have some "smart" features like altitude hold. Faster motors can interfere with these control modes, and you will not get the benefit of a faster motor like you get with a "sport" quad like the older X4s, where you have direct control over the throttle.
If you want to use our motor in the 107P or 107D+, you need to use a different flight controller, otherwise you will see strange side effects, e.g. the inability to land.