PCO preforms are used for the manufacture of PET bottles for the packaging of carbonated soft drinks and juices. PCO neck finish is also available in a short variant with fewer threads. Both have a 28mm neck diameter. PET Preforms are a fast and easy way of manufacturing PET bottles. PCO preforms are used for the manufacture of PET bottles for the packaging of carbonated soft drinks and juices. PCR preform comes in two variants, the standard, and the short PCO. They also come in a wide range of weights, ranging from 12 grams to 54 grams.