SR20DET question

[dummy240sx]

http://driftjapan.com/blog/wp-content/uploads/2007/10/nissan-sr20det-engine-drift-japan-blog-small.jpg

what is the filter located next to the valve cover in this picture.
Ive noticed some SR20det's have just more tubing there, some have filters and some have nothing at all.

My question would be:
what is the filter and what is it connected to?
What is its purpose?

[nismoman]

It is a breather filter it shouldn't be there. It should have a hose hooked to the intake pipe

[dummy240sx]

On my motor, i currently dont even have the filter. it is just an open hose.
Is this causing any damage to the motor?

[nismoman]

Well it probably won't cause alot of damage but there needs to be a vaccum there. You def don't want dirt going in there though. Just hook a hose up to the intake between the maf and turbo.