What the U400 replaces at your door
- Before bringing it home: confirm you have a Thread-enabled Apple Home hub and a compatible iPhone or Apple Watch for UWB unlocking.
- Apple home key tap-to-unlock works with an Apple Thread-enabled Matter controller, such as recent HomePod or Apple TV 4K models.
- NFC cards are sold separately, and a Thread-enabled Matter controller is required for each platform you want to use.
If you regularly arrive with your hands full, the Aqara UWB Smart Lock U400 is built to let you skip the key entirely. With a Thread-enabled Apple Home hub and a compatible iPhone or Apple Watch, ultra-wideband detects you coming and unlocks automatically, so you do not have to fumble for a phone when you are carrying groceries or wearing gloves.
Not an Apple household? You still get plenty of ways in. Apple home key, fingerprint, touchscreen passcode, voice assistant control, the app and a physical key all work, and an NFC card is supported if you buy one separately. Our advice is to treat UWB as the bonus, not the reason to buy, because UWB unlocking depends on an Apple Watch Series 6 or newer, aside from the SE, or an iPhone 11 or newer, aside from the SE and 16e.
Matter over Thread lets the lock talk to more than one platform at once, but each ecosystem needs its own Thread-enabled Matter controller. If your smart home is built around a different system, check that controller requirement before you order.
What $219.99 buys you here
At $219.99, this U400 is $49.84 below the typical price of $269.83 over the last 90 days, an 18 percent difference. It is also the lowest price we have on record for this lock, with that all-time low being $219.99.
The price covers the lock and its rechargeable battery, nothing more. Factor in an NFC card only if you want that option, and budget for the hub if you do not already own a compatible one, since the headline UWB feature leans on it.
| Offer detail | Recorded value |
|---|---|
| Amazon price | $219.99 |
| Customer rating | 4.1 |
| Customer reviews | 415 |
| Typical price over 90 days | $269.83 |
| Difference | $49.84 (18 percent) |
Room fit, charging and upkeep
The U400 is a deadbolt replacement, so it swaps into the door rather than sitting over an existing latch. It is IP65-rated outside, which means dust and water exposure on the exterior are covered, and BHMA certification speaks to its mechanical strength. Inside the app you can set auto lock, a night latch mode that limits unlocking to admins and physical keys, and do not disturb.
Power comes from a removable rechargeable lithium battery rated for up to 6 months per charge. You can top it up through the lock's USB-C port without taking the lock offline, or pull the battery and charge it elsewhere. A voice alert tells you when the battery falls below 20 percent. There is no stated cost per charge, so check your own electricity rate if you want to know the running cost.
When this lock is the wrong fit
We would skip the U400 if your household is not on Apple. The hands-free approach unlock is the standout feature, and it needs a Thread-enabled Apple Home hub plus a supported iPhone or Apple Watch, so you would pay for something you cannot use.
It is also the wrong choice if you do not want to manage a rechargeable battery. If your door hardware or rental agreement rules out replacing the deadbolt, a retrofit smart lock makes more sense. Otherwise, start by confirming your hub, your door thickness and your phone model before checkout.
Product details
| Model | DL-D16E |
|---|---|
| Color | Silver |
