A waterstop is an element of a concrete structure, intended to provide watertightness when embedded in and running through concrete joints. Waterstops are frequently manufactured from extruded plastics such as: PVC or thermoplastic elastomeric rubber (TPER); formed metal such as: stainless steel, copper, or carbon steel; or extruded thermosets such as: natural rubber, styrene butadiene rubber, or neoprene rubber.