According to your purpose, different types of GPS devices are available in the market. If you want a GPS for your vehicle, then it must have a large display screen, maps of the streets and compatibility with external antenna. You can go for a GPS navigation system which is fixed. A fixed device offers you a lot of features, more than a portable one. It will also be more rugged. You can also buy a PDA or a handheld GPS device for your car. The drawback that the portable systems have is that voice instruction are not heard properly when music is playing in the car.

Hikers should go for a handheld GPS device. A GPS device for hiking should offer a lot of features which are quite essential for hikers like it should be weather resistant, should be able to tell you about the satellite location, the height above sea level and also tell about your location with great accuracy. It should have Wide Area Augmentation System which will enhance its accuracy to 10 feet. If you have the option, you should choose a 12 channel GPS. This will be able to receive signals even in forests and other such areas. The device should of course be easy to use and carry and compact. Like all other GPS devices it should have the waypoints, should allow you to download maps and tell you about the distance traveled. It should also suggest you the shortest route etc.

If you want to buy a GPS device to keep yourself fit, you should buy the one which tells you about speed, time and distance. It should keep a track of your heart rate. It should also be weather proof. You should be able to download new fitness regimes using the computer interface and it should allow you to load maps.

Waterproofing, back tracking, marine mapping, active sonar tracking etc. are some of the features that you should look out for while buying a GPS device for boating and marine purposes.