It is NOT primarily used by the Teamsters, you dolt. Every union in NYC, from Sheetmetal workers, to electric Local 3, to the Dockbuilders, Steamfitters, to the Carpetry Union use that !@#$ing ridiculous thing every time a non-union worker does as much as steps NEAR a job site.
You dont even know the true workings of what you carry a flag so high for! LOL.