I've posted a couple of pics in this thread.
http://forums.sohc4.net/index.php?to...931.0#lastPost
Not very good pics with my phone but I think you will get the idea.
The sealing material is the pink stuff sandwiched between two hoops of corrugated metal.
The pink material stands proud of the metal hoops and is a slightly soft material.
If the pink stuff crushes a lot, the metal hoops should crush concertina style spreading inward and outwards.
I'll let you know my findings when fitted.
Sam.