Reflectix® - The Duct Insulation Spacer is a roll of reflective insulation used in conjunction with Reflectix® Duct Insulation. It consists of two 94%+ reflective layers of film bonded to two internal layers of heavy gauge polyethylene bubbles (total thickness 5/16"). Spacer is 2" wide and is offered in rolls of 25 linear feet. Spacers are easy to work with, and provide an enclosed air space between duct and insulation. The enclosed air space (and number of enclosed air spaces) determine R-value for that particular situation. Made in USA.