Tech21 Evo Endurance for iPhone 6/6S - Smokey/Black Using Lithium ceramic battery technology, EVO endurance is the world's First Ultra safe charging case. Flex shock is the worlds most advanced impact protection material which protects your customers Phone from drops of up to 2M/ 6.6ft. Evo endurance is easy to install and charging starts at the touch of a button, while an elegant LED indicator let's your customers know how much charge is remaining in the battery.