If you don't want to pay $4.50/ft for something that shouldn't cost that much, try these..
Resistant EPDM Foam, Cord, 1/2" Diameter, 100' Length
Resistant Neoprene/EPDM/SBR Foam, AdhesiveBack, 1/8" Thick, 3/4" Wide, 50' Long
They are both squishy like the $4.50 /ft material.
Glue ends together with super glue.
It's not a good deal if you have just a small hatch or port o seal, but if you have several, it's way cheaper.
For my Bomar hatches, I needed 9/16" dia gasket
, but was too cheap
to pop for the Bomar/West 10' pack. I also needed enough for 2 hatches and several opening ports
1/2" is not big enough, so I added the 1/8" flat first, then the round cord. It is important to get round cross-section; otherwise you won't be able to make the bends on the corners without deforming.
I don't remember the adhesive
but it was black, maybe 3M, maybe 8003, 8006 or similar part number. Picket it up at the one of the chain auto stores.