Logitech Case+ with +Drive add-on

As clever as smartphone cases can get, their features are usually set in stone; if you decide you need a battery pack after you bought a wallet case, you might be stuck. Logitech hopes to eliminate that accessory anxiety with its new Case+ add-on for the iPhone 5 and 5s, built in part by the TT Design Labs crew it acquired last year. The modular design starts with a basic protector, but lets you attach components depending on what you need. A +Drive piece gives you a magnetic car mount, while +Energy more than doubles your battery life; +Wallet offers space for your credit cards, and +Tilt (based on TT's TidyTilt) provides both a kickstand as well as a magnetic mount for your fridge.

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Logitech Case+ system

Do be prepared to pay for the convenience, though. Logitech currently plans to ship Case+ in the US this month as a $200 bundle that includes everything. Given that a 16GB iPhone 5s typically costs the same amount on contract, that's an expensive proposition -- it'll only make sense if you crave flexibility. We've reached out to Logitech to see if it will let you buy components one at a time like you can elsewhere, but we wouldn't count on it. If your needs aren't quite so varied, you may want to pick up a more focused (and likely cheaper) case instead.