The Reflectix 48 in. W X 50 ft. L R-3.7 to R-21 double reflective insulation is a versatile and energy efficient product. The product consists of two 94 percent reflective layers of film bonded to two internal layers of heavy gauge polyethylene bubbles.It is lightweight and easy to handle, can be installed using standard tools. This insulation helps in reducing energy costs by reflecting radiant heat, making it an excellent choice for improving the energy efficiency of your home or building.