This ultrasonic device emits a 125db piercing sound that dogs can hear - but humans cannot. Ideal for joggers, cyclists, the elderly, and anyone who comes into contact with dogs or who is nervous of them. We have sold ultrasonic dog repellers to public organisations, couriers and housing associations who use them to provide reassurance to delivery workers, meter readers etc. Alternatively, use as a training tool to reduce your dogs barking and improve behaviour. As with all products involving animal behaviour, results vary from one dog to another,and should be used in conjunction with spoken commands to reinforce the message. Features Helps keep unfriendly dogs at bay Protect your dog at walk time Safe and Humane Complete with Belt Clip Fully directional, requires 2 x AAA Batteries (not supplied - see options available) Dimensions Length 94mm Width 60mm Depth 30mm Weight 48g Frequency range: 24,000 - 26,000 Hz Range: It's difficult to give reliable data on the effective ranges of ultrasonic devices as it depends on the situation and the dog. We recommend that you activate the device as soon as you see the dog you wish to deter, regardless of how far away it is. Keep the device pointed at the dog, deploying constantly until the deterrent effect is achieved. 100% Satisfaction or your money back Just like any humane device, we can't guarantee that the Advanced Sonic Dog Repeller will be effective in all situations - that's why we provide our Satisfaction Money Back Guarantee. Simply post the device back to us so that we receive it within 30 days of your order and we'll give you a complete refund (less carriage). We're confident you won't be disappointed!