What is a spark arrestor?

[DareDevilQracer]

Some places sell silencers without them and I was wondering what they do.

[flaneledholes]

It is at the end of a muffler on a quad... It is there so you wont hurt the enviroment so much...It is removable for that little extra push...

[timewass]

It's simply a device the forestry people like since it does xactly what it says it is. it arrests(stops) sparks from exiting the pipe.

[ATV_MAN]

Its a piece inside the back of some pipes(all stock pipes have them)that is removable to increase top speed and reduce bottom end because less backpressure.It also makes the quad louder when taken out.

[PismoGuy400]

all it is is something to stop sparks from being shot out the muffler w/ the exaust.