This $16 app turns your iPad Pro into a PC or Mac monitor

I may be a journalist, but my desk looks like it belongs to a stock trader. My 27-inch iMac has two external Dell monitors, one 19 inches and one 24 inches. And thanks to the Duet Display app, I sometimes add a fourth screen: my 12.9-inch iPad Pro.

Duet Display is a $16 iOS app that turns any iPhone or iPad into an external monitor for Windows or Mac computers, and it works in both extended desktop and mirror modes.

Here are five good reasons why the app is worth the slightly steep price.

1. iPad Pro is big and beautiful

Apple’s iPad Pro is the best possible, portable external monitor. The sizable Retina screen gives you plenty of real estate to view documents, websites or anything else.

2. Duet Display (mostly) doesn’t lag

Duet Display connects your iPad to your computer via an app for Mac or Windows, using a Lightning or 30-pin USB cable. Duet Display connects via a wire, so there’s isn’t much lag. I did notice a bit of lag time when I clicked around through folders in the Mac OS X Finder. It was a little annoying, but overall the value it provides is worth the minor headaches.

3. Duet Display makes you more productive

If you frequently work on the road and own an iPad Air or Pro, you should seriously consider Duet Display. The ability to use two screens (say, an iPad and a laptop) in a hotel room, conference area or other venue makes you much more productive. If nothing else, you reduce or even eliminate the need to switch back and forth between apps, which can help you concentrate and work more efficiently.

4. Duet Display improves presos

I also recommend Duet Display for salespeople, real estate agents, and anyone else who gives on-the-go presentations. You can turn the iPad Pro monitor to face your audience and mirror the display to drive your presentation, so you all see the same thing.

5. Duet Display is the perfect fourth screen

As mentioned, I connect my iPad Pro to my iMac, turning it into a fourth monitor for my desk. That may sound excessive, but you’d be surprised just how easy it is to put that fourth screen to good use.

To sum this all up, if you really want an iPad Pro but haven’t been able to justifying the hefty price tag ($799 and up), Duet Display could ease the decision making process because it makes the tablet even more useful.