A friend of mine runs the Dinotte 400R. We passed each other in opposite directions last summer and stopped to talk a while. After our conversation, he continued in his direction, and I stayed put to observe his tail light in broad daylight. At 0.5 miles distance, his tail light was still very obvious. I run either two or three Super Flashes, but I don't run them during the day unless it's really gray/overcast. They're plenty at night.