Pest Free simply plugs in to any household power point. When switched on it alters the existing electromagnetic field in your electrical wiring, reaching deep into the walls, ceilings, cupboards and crevices affecting the pests, making your home a "no-go" zone - You only need one Pest Free for the average 3 bedroom home. Pest Free does not effect humans or animals only drives pests away by disturbing their natural breeding and eating cycle. Certified by Off ice of Energy as meeting Electrical Australian Safety Standards. (Certificate No. CS 6455N). The cost to run Pest Free is less than a 7 watt light bulb and this quality "Australian Made Product" at $89.95 is great value for your home and much .better for the environmant. Pest Free goes to work as soon as you switch it on. You will most likely see an intense in activity throughout your home. But gradually they move out - it will not affect insects that fly into your home, however Pest Free will stop pests from nesting and breeding where chemical sprays, powders, baits and ultra sounds can't reach. Under normal conditions your Pest Free unit will last for many years and comes with a full 3 Year Warranty against parts and labour making it a valuble investment for your home or business. Yes, ultrasound devices only work when the pests get within their store range. Pest Free works throughout your home or business at all times. Within thirty days after you receive your unit you may return it to us if for any reason you are not completely satisfied. We will refund the amount paid (less postage) with no questions asked.