Principle: Readings display the powerful voltage determined by the typical price of samples in excess of a complete quantity of periods of the elemental frequencyV?y nên nhà cái 123b ch? c?n có b?t k? hành ??ng gian l?n hay l?a ??o nào ??u s? b? tr?ng ph?t ho?c b? ng?ng ho?t ??ng ngay l?p t?c, ?? b?o v? quy?n l?i cho ng??i ch?i.Trong tr??ng h