The ReCo process was mainly developed to run Post Consumer Reclaim (PCR) material. In this case the parison consists of 3 layers. It has basically evolved by taking the DeCo process a step further. An additional virgin inner layer is added to prevent the filled product from contacting the regrind or recycled material.
The ReCo process only allows a combination of materials from the same family of resins.
In case of food packaging, the middle layer can also be colored black for UV protection.