I am looking for a type of rubber seal to fit an 1\8" wide & deep slot?

Question

This is to form an air tight seal between two surfaces.

Answer 1

Try these links
http://www.alliedseals.com/
http://www.bestrestproducts.com
http://www.manvillerubber.com/products_5.html

Answer 2

Try an "O" ring available at your hardware store in many different sizes. These can be cut to length and make excellent seals. You can also buy vulcanized rubber compound which you can mold into the shape you want, this may be a little more complex but is an option.