Pest repellent device (mosquitoes, flies, moths, rats, mice, spiders, cockroaches). Just plug it into electricity, no smells, no noise. Works with colors: Red color: electromagnetic waves Yellow color: ions Green color: ultrasonic The three colors together provide electromagnetic waves, ions, and ultrasonic. Excellent for owners of farms, rest houses, and homes. Warranty expired, the device is from Saco. Honestly, it was only used once and then forgotten.