As soon as assembly groups leave the laboratory, they should be protected against any harmful external effects. These include damage caused by touching the assembly group (ESD), but also damage which may occur during operation when interferences in supply or data lines make their way into the device or assembly group. Voltage spikes such as those caused by ESD are very steep and may achieve levels of more than 10 KV, but usually contain little energy. Components with very fast response behavior are required to protect against such spikes, but they must not have a negative effect on the signal quality of connected lines. The solution is glass-ceramic ESD suppressors. At less than 0.1p F at 1 MHz, they have very low self-capacitance and can thus also be used to protect high-speed signals such as USB 3.0 and HDMI. Varistors are the protection component of choice against overvoltages in supply lines. They do not respond quite as quickly as ESD protection elements, but can dissipate significantly higher loads.