Vortex Telescopic Vents are an adjustable and telescopic vent system designed by Mar-flex Waterproofing and Building Products. These vents are versatile, needing much less inventory space, because our vents’ two sizes fit nearly every foundation wall. Vortex vents also are built with high-density polyethylene, guaranteeing durability. Users can adjust airflow using easy-to-access controls built right onto the vent, and Mar-flex manufactures these vents in two adjustable sizes. The Vortex Thin Manual adjusts from 4.75 to 7 inches and the Vortex Manual adjusts from 7.5 to 10 inches.