hose that comes from valve cover to intake?
 

I see some cars that have there own little air filter conected to the valve cover instead of a hose that connects to the intake pipe.. What's the point of them?
is it a performance thing?

all it is for crankcase ventilation. it doesnt need to be hooked to the intake so people just put a filter on it.

k, i just orderd one of them filters.