Battery cases are ubiquitous, with no shortage of options if your iPhone 6 or 6s needs help getting through the day. If you're looking for something pocketable and cheap, Mophie's Juice Pack Reserve for the 6 and 6s might be right for you. It's even slimmer than the company's Juice Pack Air (despite the name), and at $60, it's almost half as expensive as Apple's option. I personally find its sleek, curved chassis a more comfortable to hold, but be warned: It packs a slightly smaller 1,840mAh battery. Like most other options, though, it uses a micro-USB port to charge so you can't transfer power and data while the iPhone's inside it. Too rich for your blood? We (and our friends at The Wirecutter) are also fond of Anker's Ultra Slim Extended Battery Case, thanks to its slim 0.53-inch design and relatively large 2,850mAh cell. Not too shabby for $40.