Polypropylene is a plastic type with low specific gravity. This plastic, whose short name is "pp", is also the raw material of gelatin. In recent years, since it has been melted together with ultraviolet protectors, its resistance to sunlight has increased. The shrinkage of polypropylene, which is one of the most used thermo plastics in the industrial field, is between 0.006 mm and 0.02 mm.

Before the use of this type of plastic became widespread, a chemical called polyethylene was used in indoor heating installations. Polypropylene is easier to produce than polyethylene and its heat resistance is much higher. For this reason, this material is mainly used in many installations, especially indoor installation systems.