What the heck is....

[Buechse_Germany]

...a spark arrester??

sorry guys bit im german and i dont think my english is good enough to translate this....

thx for help

[Jeb]

Its a part of a muffler that keeps sparks from getting out of your exhaust. Basically to keep you from starting a fire when riding around dry vegetation.

[Buechse_Germany]

cool and does someone know where to get those things?

[TimSr]

They are built into most stock exhausts, and many aftermarket ones, so yours may already have one. The idea is to prevent fires, and many public riding areas here require them. Most catalog order places that sell pipes also have add on spark arresters which basically consist of a screen.