Apple Smart Battery Case (for iPhone 6s) - Charcoal Gray The Smart Battery Case is engineered specifically for iPhone 6s and iPhone 6 to give you even longer battery life and protection. The soft microfiber lining on the inside helps protect your iPhone, while the soft elastomer hinge design makes it easy to put the case on and take it off again. On the outside, the silky, soft-touch finish of the silicone exterior feels great in your hand.