This was a gift. I have never used it. I was told it was purchased on Amazon, so I've included the product details from the page. It's not meant to kill insects, but rather to repel them with ultrasonic waves. The photos show some that can be worn like a wristwatch, but the one I have is not the wristwatch type; it's more like a keychain. Insects, pests, insect repellent, extermination, ultrasonic, device