Fitbit Zip is a small clip-on fitness tracker that tracks steps, distance walked, and calories burned. The Fitbit platform allows you to manually input a variety of other stats to get more precise results.
Pro Easy to hide under your clothes
The Fitbit Zip fitness tracker is very small, so you can easily wear it somewhere that it will be hidden (belt, pocket, bra strap, etc.). Unlike most pedometers with wrist bands, you don't have to worry about trying to make it blend in with what you're wearing.
Pro Records essential fitness data
Besides total number of steps, this pedometer records the distance you walked (in miles or kilometers), calories burned (taking into account the number of calories we burn even being inactive), and indicates how close you are to reaching your daily fitness goal with a smiley face. You can disable screens you don’t need in the app.
Pro Comes with a secure rubber case
The pedometer can be put in a rubber holder with a clip that you can attach to you belt/pocket. It protects the pedometer against breaking if it falls. It holds the tracker securely, so there is very little chance of it popping out of the rubber case.
Con Issues with the battery not working
The contacts in the device are very sensitive. If you don't place the battery in just right, it will only work for a short period of time before the battery needs to be readjusted or replaced.
Even when following instructions provided by the company, some people report that still can't get it working properly. The battery may end up lasting days instead of the promised 4-6 months.
You can see how to properly change the battery here.