Vorson calls its Bookmark "the world’s thinnest battery backup," and while we hear this kind of hyperbole on a daily basis, we're inclined to believe that even if this one isn't the very thinnest, it's darn close. The colorful plastic body tapers down from about a centimeter to only 4.7mm at the other end; it's just bit taller than an iPhone 5 or 5s, and a little bit wider. There's a 2500mAh cell inside, but the output is only 1A, so it's best suited…
