How long do we fly our flags at half mask?

In memory of the nine firemen that died in the fire in Charleston SC, we were asked to fly our flags at half mask. My question is how long do we fly our flags at half mask?How long do we fly our flags at half mask?
you meen half mast or half staff.





oh and please don't listen to mrealy2...hes an idiot. The U.S. is in the best condition of any country. Hes letting this get political and should be shot. Countries like Sudan are in poor condition the f*****g idiot.How long do we fly our flags at half mask?
Since the U.S. is in poor condition, over-all, the flags should remain at half-mast.
Half mask? Please attend summer school.
Wow. I'm sorry that our education system failed you.