Purchased in October. I bought three, and since I'm not using two of them, I'm putting them up for sale. This product can powerfully enhance the filtering effect of a power distributor with a noise filter. It was created with the aim of being affordable and widely improving power environments. To use, simply plug it into an empty terminal of your power distributor. You should notice the sound changing within a few seconds, with the contours of the low frequencies becoming clearer. Compatible voltage: ~AC120V