RS PRO 20A 250 V ac, Chassis Mount EMI Filter, Single Phase

a compact component that can be connected to electrical devices to prevent external radio frequencies from impairing performance.
This power line filter significantly reduces the amount of conducted frequencies between your equipment and the connecting power line. RFI can cause permanent damage to electronic circuits, so filtering them out is crucial to prolong the working life of your devices. The filter also protects against transient voltage spikes, which can result from power outages, short circuits, and nearby lightning strikes.