& : Ultrasonic Pest Repeller physically eradicate insects and pests without chemical or toxic material. No odors, non-toxic and zap-free, which is safer for pets and kids. & The ultrasonic waves are only identified by insects, free of radiation, smell and noise. Just plug this pest reject into the socket and vertical to the floor. : The Insect & Rodent Repell-ent can be placed in house rooms such as the living room, kitchen, bedroom or office. Since ultrasonic waves cannot penetrate walls and solid objects, it is recommended to put one in every room. , : Nothing can ruin a perfect day outside like emergence of pests, pest control ultrasonic repel-lent are one way to tackle this pest problem. In general, it takes 3-4 weeks to make effect.