FDA approved compounds. For use in holding tank connection, sanitation vent and toilet systems. Smooth extra heavy-duty PVC tube, reinforced with PVC helical rod. Made with specially formulated FDA approved material to provide excellent resistance to odor permeation and toilet chemicals. Not recommended for use in alcohol, anti-freeze, petrochemical, potable water, solvent or pressurized water systems. Temperature range -40F to 160F (-40C to 71C).