Review on 2021 Upgraded Ultrasonic Pest Repeller: 8-Pack Ultrasound Plug-in Pest 🐜 Control for Home, Office, Kitchen, Warehouse, Hotel - Effective Electronic Insect Repellent by Amanda Johnson

I bought them mainly for flies and spiders. It was hoped that they would help eliminate some of them, but they are not helping. I am not satisfied with the conditions under which you can make a return, less than a month. According to the product description, it works for up to 4 weeks. I've had them for 2 months and now I can't ask for a return/refund knowing they're no help.