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.

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. Output comes through at up to 1,920-by-1,200 resolution at 60 frames per second.

The third USB port will accept flash drives or hard drives, and suddenly it's Windows 10! Attaching a keyboard and mouse makes it more powerful. 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. Back when Microsoft launched the Lumia 950 and 950XL they also launched the Microsoft Display Dock (HD-500) designed to enable a desktop like experience from your phone by using it to connect up to a keyboard, mouse and monitor. 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. The Surface Dock is a great way of expanding a Surface but it is a premium device costing around 170. On the back, there are three USB-A ports, a USB-C port for power, an HDMI out, and a full-sized DisplayPort connector. On the front, there's a USB-C port that connects to your phone. 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. The $99 Microsoft Display Dock HD-500 is a better option.

Microsoft display dock alternatives