Product: PEX Hot and Cold Water Piping System. Brand: AIS. Model: 16 mm. Description: PEX hot and cold water piping system. 16 mm diameter pipe. Product: PEX Hot and Cold Water Piping System. Brand: AIS. Model: 20 mm. Description: PEX hot and cold water piping system. 20 mm diameter pipe. Product: PEX Hot and Cold Water Piping System. Brand: AIS. Model: 25 mm. Description: PEX hot and cold water piping system. 25 mm diameter pipe. Product: PEX Hot and Cold Water Piping System. Brand: AIS. Model: 32 mm. Description: PEX hot and cold water piping system. 32 mm diameter pipe.