If you want to keep your dog around for as long as you can, it’s important you monitor their health and keep them in shape. The Whistle FIT Pet Activity Monitor helps you do just that. Whistle has partnered with Pet Insight Project with the FIT in order to help pet owners and researchers alike. This pet tracking device attaches to any collar up to one inch wide and tracks your dog’s activity, including activity, rest, and calories burned. This gives you valuable metrics so you can make adjustments to diet and exercise. The tracker runs off of a rechargeable battery that lasts two to three weeks, and the app is available on iOS and Android. Unlike other Whistle models, the FIT does not have GPS.