Aqara’s U400 smart lock boasts hands-free unlocking

Smart home device manufacturer Aqara is showing its new Smart Lock U400 at CES. It’s among the first devices of its kind to combine Apple Home Key technology with an Ultra-wideband (UWB) radio to deliver hands-free unlocking when an authorized user approaches the door.

Provided you’re wearing your Apple Watch or your iPhone is in your pocket, purse, or backpack, you won’t need to touch the deadbolt to unlock it (compatibility with other smart devices is promised down the road). The trick is made possible by an UWB radio inside the lock, along with support for Matter-over-Thread, although it will also require you to have a Thread-enabled Matter controller inside your home. For Apple Home Key users, that means an Apple TV or HomePod.

Using its UWB radio, the Aqara U400 measures time-of-flight (the precise time it takes for a radio signal to travel between the lock and your smart device) and angle-of-arrival (the direction of that radio signal) to determine your location with accuracy down to the centimeter. This ensures that the lock will only open when an authorized user is outside the home approaching the door and not simply walking past it or while they’re inside the house.

Aqara

Aqara says this approach offers better security since UWB technology is more resistant to relay attacks than Bluetooth-only proximity systems. A built-in gyroscope enables automatic locking once the door is closed, helping prevent homeowners from accidentally leaving their door unlocked. Power comes from a 7.3V rechargeable lithium-ion battery rated for up to six months of use per charge under typical conditions. If the battery runs out, the lock can be temporarily powered via USB-C from a phone or power bank for emergency unlocking.

If you’re not an Apple user, Aqara says it will add support for devices that use Samsung Wallet later in the first quarter of 2026. The Aqara Smart Lock U400 also supports tap-to-unlock via Near-field Communication (NFC, via a smartphone or an Aqara key card), as well as with the lock’s fingerprint scanner; personal codes entered on its PIN pad (including one-time and scheduled access); mobile apps; voice control through Alexa, Google Home, Samsung SmartThings, Siri; or a conventional mechanical key.

The Aqara Smart Lock U400 It uses a standard 60/70mm deadbolt and supports door thicknesses from 35mm to 55mm, making it compatible with most U.S. residential doors. The exterior keypad panel carries an IP65 rating for dust and water resistance, meaning that the lock is dustproof and can withstand being sprayed with water jets (short of a pressure washer).

The Aqara Smart Lock U400 is available now for $269.99 at Amazon or Aqara’s e-commerce site in silver or black (satin nickel and “shadow” black finishes are also promised).

This news story is part of TechHive’s in-depth coverage of the best smart locks.