Safe Turn is a simple idea well executed. Designed to be position sensitive, the rider adjusts the Safe Turn so that it begins blinking when the rider's arm is raised to indicate a turn (also when waving to passers by and swatting at flies). But, in a sport where (if riding on street) visibility is everything, the Safe Turn adds another layer of blinking visibility.
While not terribly suitable for the American single arm turn indication convention (you can adjust the Safe Turn to blink if the arm is horizontal or vertical, but not both) by wearing one on your left wrist and one on the right you can simply point in your turn direction and the following motorist will get the idea.
You turn the device off and on by depressing the yellow lens. Adjustment for position is done by turning the device on the base so that the blinker activates in any arm position you like. Light in weight, wearing two of these will not slow you down and, hey, they could save your life at night! Although visible during daylight, I am not certain they are bright enough to attract attention, but they can be seen if the motorist is looking at you.
I like wearing these on the street and the motorists get the idea, so it's all good!