Wetsuit foam rubber is Neoprene. There are so many different versions of all of these foam rubbers. Thousands. When I first started I was asked very specific, technical questions. I didn't have a clue but am MUCH more knowledgeable now. I have a large lateral file cabinet full of samples of rubber, foam rubber, gasket papers, chipboard, insulation. In fact I need a larger cabinet.

The material I used for this is a medium-low density (I can't give the specific durometer in Shore A00 scale for trade secret reasons - others will have to go through their own expensive learning curve ), EPDM foam rubber. And there are no less that 1000 versions of these foam rubbers from different manufacturers. The material I purchase is THE most expensive. About 3X similar looking, cheap neoprene that shrinks about 5% and tears relatively easily.

I'm sure the modern materials are better and more durable than anything that was available back in 1970.

I just received new samples yesterday of the gray foam rubber used on most Mopar and Ford taillight lense gaskets. Again, more expensive (the prices on these materials have gone up 250% since I started about 10 years ago). The new samples had better tensile strength, less water absorption, less compression set and still look like the OEM/NOS materials. The biggest difference is the sheets are MUCH more consistent looking from batch to batch than anything previously available. Much more consistent PPI (pores per inch) and color.