If your looking to replace the black fabric reinforced material that is riveted to your firewall ?

It's 1-1/2 wide  x 84 long
There is a black silicone replacement Smooth( Reiinforced Fiberglass ) available
Mil spec: AMS3320-G-093

STOCKING DEALERS:
Sacaramento Sky Ranch 800-433-3564 ( Northern Calif )
ElCajon Aircraft 619-448-9000      ( So Calif )
TrimCraft Aviation 800-558-9405     (   Wisc )
Aircraft Spruce    877-4-spruce     ( Two Locations )

This seal is rivet in place with 3/32 x 7 Rivets with a metal strip at the bottom

I hope this helps !