I purchased this set of door and window alarms, and it has exceeded my expectations. They are easy to install, just stick them on with the included adhesive tape. The sound is loud and loud enough to alert in case of intrusion. I like that they are compact and discreet, yet effective. Plus, they are battery operated, so you don't have to rely on wires or complicated installations. Overall, a great option to reinforce home security at an affordable price. Highly recommended!