Do they make an Air Tight Damper?

I'm looking to divert some air form the Existing HVAC Ducts, but do not want
to have air from both Directions at the same time. I know they make Dampers
that are used for zoning, but they are not air tight. I'm not needing Super
Air Tight, but something better then the aluminum Fin in most of the
dampers. Looking for 8", 10" and Maybe larger.

Thank you,
Scott-