Priced at $99.95, the Mophie Juice Pack for the HTC One is available in black and silver, just like the phone itself. The case protects the body of the HTC One while still showing off its "zero-gap unibody design". The Mophie Juice Pack for the HTC One is lightweight and ultra thin. The USB port remains accessible so that users can charge both the phone's internal battery and the battery in the Juice Box simultaneously.
If having all day battery life for your HTC One is important to you, you can check out the Mophie Juice Pack by clicking on the sourcelink.
source: Mophie via Engadget