Whistle Labs produces and markets the Whistle GPS Pet Tracker, a device worn on a pet's collar that monitors its activity and location. The Whistle Activity Monitor tracks the duration, time, and intensity of a pet's exercise then gives the data to users over Wi-Fi networks or to a phone app using Bluetooth. The GPS pet tracker is for finding lost pets. It also produces an alert if the pet's behaviour changes, for example, a reduction in sleep, indicating anxiety.