The name chlorosulfonated polyethylene refers to a broad group of chlorinated elastomers. These chemicals are also often referred to as CSM, synthetic rubber or Hypalon, which is the brand name that the chemical is marketed by DuPont, the company that first developed it. CSM contains 27-45% chlorine, which gives the chemical many properties. Chlorosulfonated polyethylene is widely recognized for its chemical resistance.