A base station, wireless headset and headband, the headset being powered by a rechargeable battery, the base station having a cradle with charging output points, and the headset having a cradle-neck with charging input contact points. In the method, the domain information is encrypted and the encrypted domain information is stored in a predetermined storage device in the domain the encrypted domain information to the predetermined storage device, thereby securely backing up the domain information without the help of an external network. Opposite ends of the carrier are fixed to respective front and back covers of the book, which can be closed against opposite sides of the stack of envelopes when the carrier is folded. The head section is articulatable about a pivot axis that extends transverse to the central axis. The capacitive devices are adaptable to a wide range of electrode diameters and electrode stack lengths.