This technique is divided into two stages i.e. single stage and two-stage process. Single stage process is carried out in two ways, 3-station and 4-station machine. The two stage process, the plastic is molded in to a ‘Preform’ using injection molding. The preform is produced using necks of the bottles including threads. The preform is then packed and after cooling is put inside the reheat stretch blow molding machine. The preform is heated above the glass transition temperature and blown using high-pressure air. A part of the process includes stretching the preform with a core rod. Injection stretch blow molding is used when high-volumes of bottles are to be produced.