This product will remove moisture trapped inside double-pane windows. IGU stands for Insulated Glass Unit, which are very common, both in residential and commercial. After a few years, however the seal often fails or the desiccant inside the window becomes saturated. Moisture then becomes trapped and unsightly. This type of restoration work requires specialized training, tools, and one-way valves. A small hole is drilled in the top and bottom of the glass, and the diluted IGU Cleaning Agent is flushed through. After Drying, one-way valves are placed into the two small holes to finish the job.