A headset capable of being donned with one hand comprises a headband with a variety of possible hinges disposed between the edges of the headband. The insulating layers include all insulating layer having a mount surface on which the light source is mounted with the electrode and the heat radiation terminal therebetween. The disclosure also includes electro-optical devices, including electro-optical devices comprising aligned chiral smectic C* ferroelectric LC main-chain polymer glasses. The police car is equipped with a receiver and a display to display information concerning the stolen vehicle. These embodiments enable a network to have additional security while consuming low amounts of power.