Also now typically a metal flag is the blue flag placed on the ends of equipment that is being worked on. The ones at least we have at SVRy are metal with "men working" stenciled in white on the blue. We have also use blue metal flags that mount on the rail to "protect" an area where we are working from anyone moving equipment into it. I did some volunteer work on some pass. cars on a local shortline a while back. I needed to go under the cars to work on wiring and started looking about for blue flags. There's were simply blue pastic fabric on short wooden dowels. Not as convenient to hook onto something as the metal ones which have a hook on top, but funtional at any rate.