THERMO MANUFACTURING ThermoPan Joist Liner is a high-quality sheet metal alternative designed for constructing return air ducts between joists and stud cavities. Made from corrugated insulation faced with aluminum, it effectively reduces duct noise and labor costs. This lightweight, pre-cut liner requires no shop fabrication, ensuring easy installation. ThermoPan offers a fire-resistant, eco-friendly solution with moisture treatment and positive R-value for improved energy efficiency. Available in various sizes, it provides an all-purpose solution for HVAC systems while sealing plenum air tightly.