It's called a wall cap. I used one sold by Thermador. Yours would be called WC8. Best price I found was $89.
Casey

I went to my local HVAC store and bought one for about $20. It doesn't have to be a certain brand as they all fit on the 8 inch duct. It has a flap on it that opens when you use it. The edges must be caulked too.

This is a fairly easy thing to get, although I have a Vent a Hood and I'm pretty sure you need to use a Vent a Hood termination cap. It was something like $30 I think.

Speaking of termination caps, do all you that have them always hear the banging of the outside vent of your termination cap? Even with barely any wind, I hear it tap tapping away, and obviously more so in legitimate wind.

I can't believe KD is not supplying the termnation cap when supplying everything else. Often a termination is supplied by the manufacturer where you are getting everything else, that way you can ensure it is matched to your components. It is also best for the tech to install at the same time. I would ask KD to supply and charge for it if it was not in their original price...but they are not pricey usually.

keitel - I never hear mine. It has a very light hinge spring that holds it snug when not in use I think.

keitel, also my term cap is enclosed in a little wedge shaped housing so the wind can't get to it so I am sure that helps too.

Mine's inside a wedge thingy too. Still hear it all the time though. I guess I'll look into it a bit more. Thanks.