Polyvinyl chloride (CAS NO.9002-86-2) is the third most widely used thermoplastic polymer after polyethylene and polypropylene. PVC's intrinsic properties make it suitable for a wide variety of applications. It can be made softer and more flexible by the addition of plasticizers, the most widely-used being phthalates. In this form, it is used in clothing and upholstery, and to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable insulation. It is also commonly used in figurines and in inflatable products such as pool toys, waterbeds, and Inflatable structures. Around the world, over 50% of it manufactured is used in construction. As a building material, PVC is cheap, durable, and easy to assemble. It is also biologically and chemically resistant, making it the plastic of choice for most household sewerage pipes and other pipe applications where corrosion would limit the use of metal.