I had problems with the thick foam weather stripping not forming a good seal. It required too much force to hold down and leaked a lot. I ended up switching over to that EDPM rubber stripping material. Its the same stuff as in car doors. My two cents anyway.

: I'm looking for 5/16" thick..... might be a problem!

: I did read somewhere (probably here) that the marine grade closed
: foam strip gives a better seal. ACE doesn't have that, at least
: in these parts. Maybe Harbor Freight?