YardGard® YG03 Alarm System, 120 dB siren. If you have a fence installed around your pool or yard, you’ve already taken a great first step towards safety. But as children grow up, they are eventually able to open the gates by themselves. A pool gate alarm from YardGard® sends a signal whenever the gate is opened, so you can better prevent children from wandering into an unsupervised pool area, where they risk falling in. This battery-operated fence gate safety alarm is an affordable yet effective alarm system that will deliver a 120-decibel signal whenever someone unexpectedly opens the gate or door. The alert sounds automatically and without delay unless you activate the one-touch adult bypass, which causes a convenient seven-second delay for authorized entry.