A pacifier that tells you the temperature of your baby. A lamp that knows when you are home and turns on by itself. A thermostat that lowers the heat to save you money.

In the brave new world of smart devices, just about every electronic gadget in your home will connect up. It's no surprise then that the simple combo lock you used in high school is now getting the Internet of Things treatment.

A Utah company called Fūz Designs (as in, "fuse") has taken on the challenge of making a smart padlock that unlocks via an app on any iPhone, Android phone, or Windows phone with Bluetooth 4.0. While seemingly simple, it's a daunting ask for one big reason: Unlike your Bluetooth headset or your Jambox, which can exhibit a few pairing or signal hiccups with no great consequences, a lock has to work all the time, every time, without fail. Lock up your bike with a keyless Bluetooth lock and suddenly it refuses to operate properly? You're stranded—or worse, bikeless.

I'm happy to report that it does work, locking and unlocking on command without problems. The device is rather expensive at $60, but it should appeal to anyone seeking a keyless lifestyle—either by proactive choice, or simply because they're the type of person who's always losing their keys anyway.

Fūz Designs calls its padlock the Noke (as in, "no key"). The design is simple, which is important. It looks innocuous, with a silver or black shell and no obvious markings. Look closer and you'll see the Fūz logo on one side with a small LED over the "u," and two small dimples on the other.

>You don't have to fish out your phone or type in a combination—as soon as you press the shackle to open the lock, the Noke looks for a known (paired) phone with the proper permissions in the vicinity.

To use the Noke, I first had to sync it to my iPhone 6. You can use any iPhone, Android, or Windows phone that supports Bluetooth 4.0. I installed the Noke app, searched for the lock, and synced up. Done. Now you can put your phone away in your pocket or purse. To unlock the Noke, just press down on the shackle (the ringed part of the actual lock) until the little LED on the face lights up green, then pull it open. To lock, you push down on the shackle until the light glows red.

You don't have to fish out your phone or type in a combination—as soon as you press the shackle to open the lock, the Noke looks for a known (paired) phone with the proper permissions in the vicinity. In my tests, I was able to lock and unlock the Noke as long as my phone was within a range of about 15 feet.

As a backup (like if your phone is kaput), you're asked to program a combination when you first set up the lock. The combination consists of a sequence of short and long presses on the shackle. You configure this in the app and change it whenever you need to. The code has to have between six and 16 presses. For example, I used a short-short-short-long-long-long sequence as a way to unlock the Noke. You can even create a code that follows the rhythm of a song.

The Noke itself is powered a standard 2032 watch battery you can grab at any drugstore, and should last about a year. But what if the battery on the Noke dies? You can't replace the battery unless you open the lock. Fūz Designs created an ingenious workaround: below the lock, there's a terminal you can use with the new battery for temporary power. Much nicer than a bolt cutter, right?

In the app, I could see a list of Noke locks with unique names–that's handy, because you could have a dozen of them and keep track of which padlocks are unlocked. Also, you can "share" the lock with others. So, if your neighbor needs to access your tool shed on occasion, you can share the lock. He or she just downloads the app and registers, then has access to lock and unlock either all the time, just once, or as often as they'd like until you revoke access. When folks use your locks, you get a notification and can even go into the app and see the GPS location of that lock.

I tested mine by locking my laptop bag to a desk using a cable. Every time I walked up and pushed the shackle, it unlocked. Simple. Later, when I worked at a coffee shop and left the lock at home, I shared the lock with my friend inside the app. She used her iPhone 6 to unlock the Noke.

The lock I tested was very close to final, but made of aluminum. The final version, which will ship in June, is made of hardened steel and boron and weighs 9 ounces. A company rep from Fūz Designs says major lock manufacturers rate their locks on a scale of one to ten, and the Noke rates a 7, which should be enough to protect a bike, a gate, or a storage unit, and that you'd need a large bolt cutter to snap off the shackle. It's even water resistant.

The lock comes in gray or black. You can get a two-pack for $55 each, or just one for $60. Yes, that's very expensive for a lock, but the keyless entry is more than just a gimmick. Honestly, the Noke is worth it for me because I forget keys and combinations so easily. I'd buy one just for the Bluetooth feature alone. But sharing locks with friends opens up a world of opportunity, and I especially liked looking up the lock and seeing it on a map, which is another way to keep track of my stuff (and my sanity).

If the lock had built-in Wi-Fi, it might be easier to send unlock codes over the Internet, but you can always use the sequence code. Plus, if it had Wi-Fi, the battery would not last nearly as long. In all, I can't gripe about a product this smart that does something so useful.