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Have any of you had any experience with these? Supposedly, they're units you plug into your wall that broadcast a frequency inaudible to human hearing, but drives pests mad and out of your home. My folks got some from Lowes a while back, but so far each summer has been the same - bugs in and out. Maybe we got a knock-off or something, I'm not sure. My brother has a friend who bought some, and successfully kept the roaches out of his apartment. Has anyone here had positive/negative results from such, and if positive, please name what brand you purchased.