Meet the SunFriend Personal UV Monitor: a waterproof UV activity monitor to help you stay safe outdoors. It helps you optimize vitamin D from the sun while preventing overexposure. You can customize it for your skin color. When you reach your daily limit of UV exposure, its LEDs flash to alert you. The SunFriend is waterproof to 3 meters.
To get started, simply set your personal skin color and sensitivity. When all the LEDs light up and start flashing, you are done. This elegant UV monitor sets you back under $50 at this time.