Neoprene, the common name for Chloroprene Rubber, was invented by Wallace Hume Carothers in 1930 for DuPont, and first manufactured in 1931 as "Duprene." This was the pioneering corporate research endeavor, resulting in the first synthetic rubber, and precursor to many new advances in synthetic fabrics and fibers.
Neoprene has substantial advantages over natural rubber in that it is more resistant to water, heat, corrosion, abrasion, solvents and oils, provides excellent insulation against cold, and is more flexible. It is used extensively for the manufacture of many items from tires to gaskets, and is an excellent choice for deep sea divers, and other applications where insulation and waterproofing are required.
Another insulating foam product that is very similar to Chloroprene Rubber (Neoprene), is Styrene Butadiene Rubber. Although visually indistinguishable from Neoprene, this product does not perform as well as an insulating waterproofing. It is more economical than Neoprene and frequently used for medical braces, "cozies," mouse pads, etc.
If you are unsure whether you have Chloroprene (CR), or Styrene butadiene (SBR) Rubber, a reliable test is to cut a tiny sliver (about 1/8" wide and ?" long), hold it in pliers, and put it to a flame. CR (Neoprene) is self-extinguishing, and will not flame.