Power filter function is through the power line access power filter, Get a specific frequency of the power signal, or eliminate a specific frequency power signal. By using this feature of the power filter, a square wave complex or complex noise passing through the power filter can be converted into a sine wave of a specific frequency. How It Works - The mains filter is a passive bi-directional network with one end of the mains power supply and the other end of the mains filter. The greater the impedance mismatch between the input and output sides of the power filter and the power and load sides, the more effective the attenuation of electromagnetic interference. The filter current up to 4400 watts EMI high-frequency power filter finished purifier socket, the coil diameter up to 31 mm! Maximum 20A current allowed! This 20A power filter current up to 4400W, 1.4MM diameter electric coil, high 31MM. Maximum current 20A, double-sided 1.6 tin plate! Note:Due to different factory batches, slight differences in appearance will not affect usage. Colour:As Shown Material:ABS Package Contents: 1 * EMI Power Filter 8 * screws 4 * rubber caps Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.