ballast hydroponic air duct 1.reasonable price,we are manufacturer 2.pay attention to the quality as life 3. Add-on service ballast hydroponic air duct Constructed of a heavy duty 3-ply, aluminum foil laminate, encapsulating a high density, corrosion resistant wire helix, forming an air tight, easy to use, quality air connector.The product comes conveniently boxed in 25 foot lengths, compressed ...