I installed a “smart lock” on the front door of our home almost 12 years ago, it was cool but it’s a distant memory now as we look at the future in this Aqara U400 Review. The EFTM Snapshot: It’s expensive, I get that, but if you want a smart lock, this is the one. Every single possible way of unlocking your door including the most amazing which is for the latest Apple devices – just walk up and it unlocks! Key (get it) to the success of this door lock is the number of ways you can unlock it.