I used this before when I was bothered by the low-frequency vibration sound (a "vroom..." sound) from my home appliances. I am selling it because I replaced my appliances. It might be a placebo, but personally, I felt a little better. It seems to have won the Higashikuninomiya Memorial Award. Please purchase with the understanding that this is a used item. Please note that we are not responsible for any loss or accidents during shipping. (T_T)