I’ve used and tested many external batteries, and OXA Frosted Box F1 is the largest one I’ve ever come across, larger even than the 26000 mAh external battery which was the previous record holder for me. As you would expect from such a device, it can hold a LOT of juice. I’ve tested it with several small and medium electronic devices, which I had previously completely depleted. I was able to fully charge first generation iPad, iPhone 4S, iPhone 5S, Galaxy S3 and iPad Mini – all from a single charged Frosted Box F1 and with plenty of leftover charge. I have not tested it with the latest generation iPad Air, but my guess would be that Frosted Box F1 would be able to fully charge it at least three times.

The battery comes with its own power supply and all the cables you’d need in order to connect it to most PC laptops. I’ve tested it with two of my older laptops – an Acer and an HP models – and it was able to fully charge both of them. As you can expect it charging a biggish laptop can take a while, so this is not a battery that will get you to full charge in an instant. Fortunately it can still be relied upon to power your laptop while its own battery is being charged. I’ve also discovered Frosted Box F1 takes a really long time to charge – I recommend having it charged overnight.

Unfortunately, I have not been able to use this power bank to charge Mac laptops. It doesn’t come with cables and connectors that will enable it to connect to a Mac. This is not just the problem with this battery – Apple is notorious for being very proprietary with their accessory connections, and I don’t think there is an independent battery manufacturer out there with a product that will work with Macs. There are some hacks that will allow you to get around this restriction (you can buy an Apple power cord or appropriate one from your old charger), but all such tricks require certain level of familiarity with electronics and willingness to improvise.

If you have any “regular” PC laptop, chances are that this battery pack will work with it. The battery supports several different voltage outputs (5V and 19V) and comes with a gazillion adapters that can fit pretty much any laptop power input that I’ve come across.

This is a beautifully made external battery. Its metal casing is stylish, elegant and very sturdy. It is, as you would expect it, fairly large and heavy. It weighs 634 grams (not including the power brick) or almost a pound and a half. This may not be an ideal emergency battery that you carry with you everywhere in your messenger bag, but it is a great backup resource to have if you find yourself on a long business trip or vacation. In many respects this is a standout product that is in a class of its own.

One last caveat: batteries of this size can get pretty hot. Make sure you are in a well ventilated space and away from all possible flammable hazards. Personally, I would recommend having a small fan somewhere near this battery while it’s in use.