These small yet very bright LED bike tire lights easily screw on to your tire valves. When your bike wheels move, the bright LED lights start flashing. They provide great SIDE visibility. When you cross an intersection, you can be confident that drivers will see your bike. You can also use these tire valve lights for jogging strollers. They are available in Red or Blue. They are motion activated, so your batteries (included) won't get wasted. Be sure to choose the correct valve size. If you are uncertain, you most probably have American valves.