dummy side vents

Hmmmm, milled stainless ?
How would you attach them?

can i ask you blokes who have side vents a Q 
 
i just got a set   are these vents 2 piece  does the back of them where the lugs are on come away from the vent itself, or are they one piece  is there like a frame that sits inside the vent
been a while since i even seen dummy vents so not sure  if the lugs are moulded into the vent or if its a 2 piece 
 
cheers

There are four different types:

early one piece

two peice - inner pressed alloy panel ‘press riveted’ to outer cast alloy frame, attached to car with four studs on the outer frame

European two piece - as above but attached to car with two countersunk screws that go through both the inner pressed plate and the outer cast frame

later one piece pressed alloy attached with four plastic tabs