The Techko S189D Ultra Slim Safe Pool Alarm is designed to sound a loud alert when a door or gate is opened. The magnetic contact sensors are installed on the gate or door you wish to secure. Once installed, it will allow adults to pass through the protected gate or door by pressing the bypass button. Once the bypass button is pressed, the adult will have 8-12 seconds to pass through and shut the gate. The Entry Alarm is a simple solution for alerting you whenever your children and others enter and leave the pool area. The Ultra Slim Pool Safety and Entry Alarm can alternatively be used as an alert system for other door and gate entry areas in and around your home or property. This kit includes two pairs of magnetic contact sensors and an extra bypass button, ideal for doors or windows with a screen. The additional sensor allows the door or window to be open but still secured because the screen is closed. If both the door or window and screen are opened, then the alarm will trigger.