The one-ounce Trax GPS Tracker, suitable for outdoor use, comes with a silicone sleeve that helps protect it from splashes and knocks. The tracker is IP65 compliant and works in temperatures between 14 and 104 degrees Fahrenheit.

This GPS tracking device works with the satellites in the GPS, Galileo and Glonass systems. However, it has been noted by users that its accuracy is not always reliable. The device operates on GSM/GPRS quad-band networks, and it comes with a built-in SIM card that is compatible with U.S. networks.

A free pet tracking app, available for download on iOS and Android smartphones, gives you the ability to view 36 hours of history so you can see where your dog has been. You can follow your pet's tracker in real time either on a map or with the Trax augmented-reality feature. This attribute is not often found on other pet trackers and is useful.

Another handy feature on this GPS tracker for dogs is that it lets you use the camera on your smartphone to help locate your dog when you're at the park or in the woods. All you have to do is pan your phone around you, and an icon with a distance indicator pops onto the screen when the phone is pointing in the direction of the dog. A split screen shows you a map with your dog's location and a view of your surroundings.

When you're at home or traveling, the pet tracker lets you set an unlimited number of geo-zones in whatever sizes and shapes you choose. Real-time push notifications alert you when your dog has left the safe zone, and it sends out change-of-speed alerts, although there are complaints that these are sometimes delayed. The tracker can be viewed by other authorized people as long as they have downloaded the Trax app, and you can add more trackers to the app if you have more than one dog.

The pet tracker contains a 515 mAh lithium-polymer battery, and a charge lasts for one day; it has an alert when the battery is low. Included in the kit is a silicone clip for threading the tracker onto a pet collar and a mini-USB cable, which fits standard USB ports, for charging the device.

Trax include two years of free data and roaming in the initial price of the device. Once the two years is up, you have the option to continue with a monthly subscription.

The Trax pet tracker does have some glitches in the firmware that are being ironed out over time, but overall this compact, user-friendly device is well worth purchasing if it fits your needs.