Hi John,
That is a 1/2 NPT male brass fitting with a 3/8 NPT female to 3/8 NPT male to female flare 90 elbow fitting. Then it's just a 3/8 male flare off of the PCV tube into the 90 elbow.
I got those fittings from a local fastener shop in my area but I think you can find them at most hardware stores, probably in the plumbing section.
Did that answer your question?
