Padlocks are one of those everyday objects that seem ripe for the Internet of Things treatment, so it's no surprise that Master Lock has given its new line an intelligence boosting upgrade. Aimed at making forgotten combinations or lost keys a thing of the past, the company's Bluetooth-enabled smart padlocks improve security, simplify sharing and even send out tamper alerts. We've been testing two Master Lock Smart Padlocks – the all-weather, high-security 4401DLH and the lighter duty 4400D – along with the Master Lock Vault app that pairs with these devices. They're definitely smarter padlocks, but is a smart padlock for you?

On first impression, both locks feel like premium hardware. Heavy, with a solid "keypad" and with reasonably bright LEDs, neither lock feels like it's going anywhere when you yank on it. The heavy-duty D4401DLH has a rubberized exterior and a much more substantial shackle.

Setting up

While setup isn't as simple as learning a new combination, it is relatively painless. The locks can be used right out of the package with the original combination provided (to get at that combination you're going to need a knife – unless you want to break some teeth), but in order to get the most out of either padlock the Android or iOS app is essential.

To use the padlock like a conventional combination lock a "directional code" is entered on the dial, which has 4 options: up, down, right and left. It's fair to say that it can be challenging to remember the 7 digit combination, or enter it when it's raining, it's dark or your phone is out of battery.

We took the pre-digital era precaution of jotting our code on the back of a business card and tucked it in a wallet.Master Lock's manual code for the Smart Padlocks

On the other hand, when properly set up your phone becomes the key, and opening the lock just takes a tap on the lock itself, or a swipe in the app on the phone for a higher security option.

Onboarding a new lock in the app is easy and from within the app you can customize your up, down, left, right combo, create a numeric password to manage each lock and most interestingly, manage who can open your locks.


Sharing access is where the Master Lock Smart Padlock's real advantage lies. You can email a "key" to anyone with a smartphone and grant them either unlimited or time constrained access. You can also revoke access at any time. The default settings allow unlimited or AM/PM access, however we'd like to see the ability to customize these settings further and specify hours of access for each guest for each lock in our account.

Another feature that people with multiple locks and multiple users will appreciate is access history. The app keeps a detailed record of when each lock was opened and by who. It also records unsuccessful efforts to open the lock.

Should I get a Smart Padlock?

There's no question this is a well made product that in most cases offers a lot of convenience and security -- however, you will pay for it. Master Locks's standard directional combination "Speed dial" model will set you back US$7.99, whereas the 4400D Smart Padlock costs $49.99 and the 4401DLH is $59.99.

So is the extra cost worth it? For locks that require limited infrequent access by one or two people, probably not. But for locks you're opening multiple times a day, locks that require access control, or when you need the extra security of knowing who has accessed a lock and when, then it's probably well worth it.

Master Lock's promo video runs through the features of the Bluetooth Smart Padlock:

Product page: Master Lock

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