They have red flashing light-buttons that you can just clip on to your clothes...they're nearly weightless. I've gotten several for free with the names of various running-related companies stamped on the front. For some reason I can't find them (googling keeps turning up articles about people who run red lights). Also these armbands work really well. I run with a headlamp when it's dark out, more to be seen than to see with, but it's sort of a pain and doesn't stay where I want it without a hat on.