http://www.youtube.com/watch?v=u-M-HU9O_FM    

Applegate R Foam Insulation is versatile. It can be used to re-insulate older homes that contain little or no insulation, even if the wall cavity is partially filled with old, ineffective insulation. Applegate does what others can not, flowing through empty space and across old materials to completely fill the wall cavity. Applegate can be injected into the wall cavity from either the interior or from the exterior of the home. It can even be installed behind existing brick.