What are the safe charging temperature and storage requirements for the Xstream?

The headset should only be charged at room temperature between 10–25°C (50–77°F). For storage, the hearing protector must be kept in a dry, clean environment out of direct sunlight, for example in its original packaging. The operational temperature range for electronic functions is -20°C (-4°F) to +55°C (+120°F). (Page 6)