Key takeaways

• The TCL D1 Pro smart lock is available for$170.
• This smart lock features some of the most reliable and fastest palm recognition technology I've tested, and it has a rechargeable battery instead of the standard replaceable batteries.
• The TCL D1 Pro's biggest downfall is the app, which is not user-friendly for customizing settings and feels outdated.

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Palm vein recognition is becoming quite popular among smart lock manufacturers, and theTCL D1 Pro is one of the most affordable locks to feature this technology. At$170, this TCL smart lock supports six unlocking methods, including palm vein technology, remotely through the app, touch keypad, NFC key fobs, third-party voice control through Google or Alexa, and physical keys.

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The TCL D1 Pro is pretty easy to install. At 2.79 inches wide, it is slightly narrower than all the other smart locks I've tested, which isn't a great look on my beat-up door -- but the fact that this door has seen dozens of smart locks in two years isn't the lock's fault. 

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TCL D1 Pro

The TCL D1 Pro smart lock supports palm vein recognition to unlock, as well as keypad, NFC key fobs, third-party voice control, remote unlock, and physical keys. 

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Aside from the smart lock allowing for keyless entry, the TCL D1 Pro also allows touchless entry. It features biometric security through palm vein recognition to be contactless, which scans the user's palm from within three inches away to identify them according to the vein patterns. 

The lock shines a near-infrared (NIR) light when a palm is detected in front of it. NIR light penetrates the skin and is absorbed by the hemoglobin in your blood, making veins appear darker. This technology is used in medical devices to find veins for injection. The type of NIR light that the smart locks shine onto your skin is invisible to the naked eye. 

A camera or visual sensor on the lock compares the map of the vein pattern on your palm to the registered ones. If there's a match, the door unlocks within a second. The D1 Pro is swift at this task, aside from being one of the cheapest locks available with this technology. The smart lock quickly scans your palm, whether dry, wet, or even chafed, and unlocks within seconds of your arrival. 

The great thing about palm vein recognition is that it's more accurate and stable than fingerprint scanning. The veins in your palm follow a pattern that is unique to you. Unlike fingerprints, which are prone to being temporarily affected by dry skin, cuts, and more, the veins in your palm remain the same for the rest of your life, barring a significantly disfiguring event. Palm vein patterns are also internal and cannot be recognized using a photo of your hand, for example. 

Also: I tested a smart lock with facial recognition, and it spoiled every other one for me

Once you install the smart lock, you must set up an access code on the lock before connecting it to the mobile app. The instructions walk you through adding a code by pressing the reset button and following the prompts. 

I was already familiar with the Smart Life app TCL uses for this smart lock because of an intelligent dog feeder from another brand at home. The app is from Tuya, a company that provides platforms for building and managing smart devices. Many affordable smart home devices use Tuya apps, so manufacturers don't have to develop full mobile software from scratch. 

Unfortunately, the mobile app is the only downfall of the TCL D1 Pro. The app doesn't make all the lock's features and customizations easy to access and understand. It took about three minutes, at least two more than it should, to find out how to turn off the smart lock's voice response so my neighbors and I didn't have to hear "Door unlocked" every time I opened my front door.

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Instead of saying "Door unlocked by X with passcode," the mobile notifications you get with the lock's actions read, "Please note that (email address) used the code to open the front door." This isn't a big deal, but adding words to the front of the notification makes it easy to miss important events and disregard notices altogether. 

's buying advice

If you're looking for a top-notch way to secure the door to your home, business, or rental, theTCL D1 Pro is one of the best available locks for the price. At$170, this smart lock is one of the few that supports palm vein recognition, which is thus far the most advanced and secure biometric technology for smart locks. 

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You can count on the fact that you'll always get alerts for lock activity, can unlock your door remotely, and can add multiple permanent and temporary users at your will. Plus, you never have to worry about replacing the device's batteries, as the included rechargeable battery reduces the need for maintenance and waste.

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