We've had Bluetooth keyboards for years, of course. The concept hasn't really changed much - they're fragile things with multiple hinges and ribbon cables. But the models and manufacturers don't seem to stick around for long, unfortunately. ZAGG stands a chance of doing better, plus its implementation is one of the best I've seen. 

The key requirements for a really portable, pocket able, useful keyboard accessory are: 

• Foldabiity - the closed unit needs to fit in any pocket, ideally you'd forget that it's there. 
• Physical support for the device - the phablet or tablet being typed into needs to be propped up at a decent angle, and securely, so that you can see what's being typed. Well, partly, that and the propping up generates a holistic sense that you are, in fact, using a laptop. 
• Decent key size and travel - this is always going to be something of a compromise, but the larger the keys and the further they travel, the closer you'll be getting to a 'laptop' experience. 
• Stability - while typing, the keyboard shouldn't move or bounce around unduly. 
• Ease of charging - early accessories used AAA batteries, but these days microUSB and a sealed Li-Ion battery are much more common. 
• Ease of powering on and off - too many designs in the past have required me to remember the exact long press key sequence for turning on and off, or for pairing. 

Compromise is the operative word, of course, and every solution I've ever tried along these lines has failed somewhat miserably in one of these areas. The one piece designs are too large to fit in a pocket or in my 'man bag', and the folding designs often don't have any built in phone support. My previous old-time favourite was Nokia's SU-8W, but this hasn't been available for years, offered poor device (physical) support and I doubt it would be fully compatible with today's phones. ZAGG's solution here is also compromised in that the keyboard does flex a bit while typing and that the opened up keyboard really needs a book or other solid surface to rest on, but otherwise it gets closer to any other solution to fulfilling all the requirements above. 

It all starts with the size when folded though. The horizontal fold within the keyboard means that the accessory can become long and thin rather than square, as is the case with a vertical fold. Together with a QWERTY key matrix that's around 80% full size, the folded unit here can genuinely fit in any jacket pocket (if not trousers) or small gadget bag. 

The materials used are plastic throughout, to keep the weight down - there's a little too much flex to the main keyboard section though and I'd have liked to have seen thicker plastic or even aluminium here. The electronics, battery and power LED are all in the slightly thicker top section (with the ZAGG logo on it), with a fold-down kick stand at the back and with the two hinged keyboard sections connected up with no less than five ribbon cables of various widths.  

The key layout is a full five rows, though without any extras - so no page up or down, media control, and so on. Which is perfectly fine - the screen of, in this case, my Lumia 950XL is only a few inches away and propped up for easy tapping. The Ctrl and shift keys work for the usual selection, copying and pasting actions, so I'm happy. The space bar, oddly, is divided into two, but this seems to just be to improve the response - a longer key, allied to the flexing of the keyboard plane, might have led to the typical 'stuck' space bar that most of us have been plagued with at one time or another. 

In use, the horizontal hinging of the keyboard does mean that you need a flat 'something' to put it on - this will normally be an airline or train seat table, but at a pinch even a book will do just fine, as per the photo below, showing the position in which I typed this review - a humble paperback book, with the kick stand on my knees behind:

In terms of typing, the reduction to about 80% normal key pitch (14cm from Q to P on the top row) does have an impact in terms of speed, though this is balanced to some degree by the auto-text-correction built into Windows 10 Mobile and almost all other smartphone systems these days. So simple typos get ironed out automatically - in typing this review, I'd average about two mistakes per line and the majority of these were caught and corrected by the OS. I was typing into OneNote, but the same should apply to any other text-based application - certainly Windows 10's handling of Bluetooth keyboards is pretty good. I did have to tap on 'Back' after going into the application, to initially clear the on-screen keyboard, but after that the only on-screen editing elements were auto-correction suggestions and a microphone should I want to try voice input!

Power is handled elegantly on the ZAGG Pocket Keyboard - when you close the accessory up, magnets hold it closed and also shut the electronics down. Then, when you open the keyboard up again later on, the magnets detect this and power the keyboard on (you know this because the LED briefly shines green).