Return all products unique relationship with POS's Storage (only salable zones)

def get_value_product_unique(self, pos):
        """
        Return all products unique relationship with POS's Storage (only salable zones)
        """
        qs = ProductUnique.objects.filter(
            box__box_structure__zone__storage__in=pos.storage_stock.filter(storage_zones__salable=True),
            product_final=self
        )
        return qs