What are the hours of work? topamax 100 mg for weight loss Their product is a Wahooo Swim Monitor System. The system requires each swimmer to wear a headband, called a swimband. The band contains two sensors and a sonar transmitter that sends out a signal when it is submerged longer than 20 seconds. The signal triggers warning lights posted along the waterfront begin flashing yellow, and after 30 seconds, the alert turns red and a siren starts going off, alerting lifeguards that someone is in danger.