Sandbags

[CTS]

If it is a map building question:

Unfortunately i do not recall where they are exactly, but i am 100% sure that sandbags are included in the official editor. Try under "entourage" group in the GEM editor construction ( i am not sure though ). There are 4 types i think, some of them are 1/4 of the circle, there is one 1/2 circle ( so you can build a full circle yourself ) and there is a full wood reinforced sandbag circle as well.

If it is normal SP or MP game you are talking about, then i personally never heard about it...