The 511KD10J with 845V 0.4W 200pF @ 1kHz 90J 415V 320V 510V 3.5kA Radial Leaded Varistors ROHS is a surge protection device manufactured by Liown. Its function is to protect circuits from transients, such as lightning surges, spikes, and other high-voltage spikes. It is designed to handle a range of voltage from 845 V, and can withstand up to 0.4 W of power. The device also has a capacitance of 200pF @ 1kHz, indicating its ability to filter out various frequencies. It is also equipped with a 90J insulation rating, in addition to 415V, 320V, and 510V varistors. Lastly, the device is rated for up to 3.5kA radial leaded operation.