I bought this as a bird deterrent because pigeons started coming to my balcony (I bought two for about 7500 yen on Amazon, made in Germany). I'm not sure if the device was effective, but I noticed the pigeons disappeared, so I'm selling it. I cannot guarantee absolute effectiveness against all birds, including pigeons, so please understand this before purchasing if you're considering trying it. I used it for several months. You'll need a small Phillips head screwdriver to open the battery compartment on the back. Also, you'll need 6 AA batteries per unit. When you slide the switch to turn it on, a red light will illuminate, and an ultrasonic sound ("kyu-in") will emit, then it will turn off. It operates intermittently. The battery life is good (I didn't have to change the batteries while using it). - There are no instructions; just insert the batteries and turn on the switch. - The product originally came with cable ties for hanging, but these are not included this time. Please prepare a string or something similar if you want to hang it. I've included a link for a detailed explanation: ISOTRONIC 2-pack Ultrasonic Bird Repellent Battery Operated Pigeon Crow Bird Deterrent Japanese Authentic Balcony Parking Garden https://amzn.asia/d/0e1qRgHQ