Aqara U50 smart door lock review

The last thing you want to hear when you’re using a machine is some kind of grinding noise. As you’re reading that, you’re probably envisioning the sound of a car engine turning and turning and not starting or a washing machine making a loud noise that you know can’t be good. If you hear that grinding, you know something is wrong. The same goes for a smart door lock. Having to fit in a smart door lock where an existing deadbolt was can be tricky.