650 SX PCV valve

I've never seen a Motormite. Does anybody have an idea what's inside?

Would guess it is a plastic disk on a weak spring forming a one-way valve. I also have one installed the same as BillT and have had it in there for 4 years or maybe more. I did buy another one as a spare this past summer for $3.99 at Pep Boys. For that price you can crack one open and look at it. Or just change it out with every oil filter change.