The USB Cable with Charging Protection for HMT-1Z1 is an extra Micro-USB cable for data transfer and charging. The cable includes a safety box that protects the HMT-1Z1s safety circuits from power surges. These surges can damage the HMT-1Z1 and may occur when connecting the HMT1-Z1 to computers, wall chargers, car chargers, and other power sources. It is the only cable approved for charging the HMT-1Z1 and for moving files to and from the HMT-1Z1.