Usually you can see the effect within 3-4 weeks, depending on the degree of infestation.Make sure that the repeller is not obstructed by furniture or electrical appliances when in use. 3 in 1 Repelling Effect - repellent with triple ultrasonic frequency range - ultrasound, sawtooth wave & bionic wave, increases its strength to expel all indoor pests of 800-1800 ft².
eBay