The best feature in Microsoft's new Windows 10 Mobile operating system is Continuum, the ability to scale your phone up into a full-on desktop PC. It's the latest incarnation of a dream that's been around since 2011's Motorola Atrix—the ability to carry your computing power with you and for it to adapt to the form factor you need. You can make Continuum happen completely wirelessly, with a Bluetooth keyboard, a Bluetooth mouse, and a Miracast wireless display dongle. But that requires a lot of pairing, a lot of battery checking, and Miracast has latency issues even on good days.

The $99 Microsoft Display Dock HD-500 is a better option. This solid little cube measures 2.5 by 2.5 by 1 inch (HWD) and weighs 8.1 ounces, and it's absolutely covered in ports. On the front, there's a USB-C port that connects to your phone. On the back, there are three USB-A ports, a USB-C port for power, an HDMI out, and a full-sized DisplayPort connector.

Plug your Lumia 950 or Lumia 950 XL into the front of the Display Dock, and some sort of monitor into the back, and a message pops up on your phone asking if you want to switch into Continuum mode. Choose yes, and your phone's screen becomes a touchpad so you can manipulate the OS on the big screen to display documents, or play music or video, for instance. Attaching a keyboard and mouse makes it more powerful. The third USB port will accept flash drives or hard drives, and suddenly it's Windows 10!

Output comes through at up to 1,920-by-1,200 resolution at 60 frames per second. That won't drive extra-large monitors, and the fonts in Windows 10 Mobile's white-text-on-black interfaces (such as in Outlook) sometimes look a little thin, but Word and Excel are terrific. In Continuum mode, you're restricted to Continuum-compatible apps, of course, which include the Office suite, the built-in music and video apps, the file manager, and a few others. More are sure to come.

My only real complaint about this plug-and-play accessory is that most of the business monitors we have around the test lab use DVI, not HDMI or DisplayPort, for their input. That means you may need a DisplayPort-to-DVI cable, depending on your monitor choices. It would also be great if it worked with more devices (right now you're limited to the aforementioned Lumia 950 and Lumia 950 XL), but that requires more Continuum-compatible phones come to market.

I'm not that enthusiastic about the Lumia 950, because our test model was buggy and Windows 10 Mobile lacks third-party apps. But Microsoft gets the Continuum experience right, and the Display Dock makes it work in an easy, reliable, no-stress manner. If you do indeed get a new Lumia, the Dock is a great way to show what Windows 10 Mobile can do, and an Editors' Choice.