Most external solutions are simple affairs, slabs of battery with a USB port, but the Booster has a couple “interesting” tricks up its sleeve.
Keystone provides an additional USB cable to charge the unit, which can be recharged from a computer USB port or a cellphone charger. A button on the side of the Booster will show how much charge you have left. All pretty standard fare.
The real trick to the Booster comes from it’s removable plastic cover. Underneath the shell is a washable, reusable adhesive patch which you can stick to the back of your phone. The shell then attaches to the reverse side of the battery and adds a kick stand to prop your phone up in portrait orientation.
As you can imagine, this adds considerable bulk to your phone, and since the adhesive is removable, it’s a tricky proposition for pocketability. Trying to get this combo in my front pocket was difficult, and I routinely got it caught, almost separating the battery from the phone several times. This makes a lot more sense for those who keep their phones in a bag or purse.
Though the shell adds some mass, the Booster comes in smaller than a Mophie Juice Pack Powerstation (though at about half the battery capacity).
Though the sticky “feature” might be a bit dubious for some, it’s still a decent buy at a street price around $45. About what you’d pay for an internal OEM replacement battery, and you’ll be able to use it with any phone sporting a MicroUSB plug.