Has anyone tried the RAD {Rider Alert Device} lights? Mounted on the handle bars and display amber and green. Amber for lead sled to alert oncoming sleds that others are behind and green for last sled to let them know. A few years ago I saw a sled that had device on the handle bars with digits to let oncomers know how many are behind. The fellow who had them said that it never really caught on. I can see why because it seemed a little confusing. But these RAD’s are just the two colors. What are you’re thoughts?