Customers using HTC's newest flagship smartphone with a mophie juice pack can rock, talk, surf, and send for twice as long with the simple flip of a switch, receiving the benefits of double the battery life on one charge.

ENGADGET: Mophie Juice Pack for the HTC One now available Mobile

The new juice pack air allows iPhone 5 users to do more with their device on one charge, packing 1700 mAh to double the battery life of the device with the simple flip of a switch.

ENGADGET: Mophie Juice Pack Air brings an extra 1,700 mAh to iPhone 5 for $100