Mono material stand up pouches are built entirely from one polymer family, for example PE PE or PP PP. That means the layers, zipper and any valve are made from the same type too. Because there is no mix of different plastics, sorting systems recognise the pouch better, separation is easier and the material can be recycled more efficiently. You avoid combinations like PET aluminium PE, which improves recyclability a lot. Depending on your product, you usually choose PE or PP, optionally with a barrier solution that stays within the same material family.