Meet the Revolar: a smart wearable device that syncs with your smartphone and lets you send a message with your GPS location to your loved ones when you are in trouble. The Revolar hides behind your clothing and activates with the press of a button to get you out of trouble. It is waterproof and has a battery that lasts up to a year. It connects to your smartphone via Bluetooth.
This is not a regular GPS tracker. It will get your location only when you press the button. The device has a discreet design and does not get in your way. You can find out more about it on Kickstarter.