The Withings Blood Pressure Monitor is a wireless device that measures your blood pressure and your heart rate and syncs your data over Bluetooth to the Withings app on your smartphone.
The device is very easy in use: you put it on, put it around your upper arm and press the button on your smartphone. You get an immediate overview of your values on your smartphone with color code telling you whether you're doing good or not.
The device is rather expensive since it doesn't track other things than your heart rate and blood pressure, but it does track it very well.
If you're planning on sharing the devices between several smartphones and users, you might experience some trouble because the smartphone app detects the bluetooth connection automatically. If someone else in your direct neighborhood used the app last, the device will connect to that smartphone instead of yours.