Standard model great for many construction, commercial & home applications. Mountable in any orientation even upside down, moisture vented away by a 80mm duct, dry air can be ducted into spaces, self regulating for optimum use of power, performs below freezing, ideal for one man lift saving money on hire contracts. Ideal for flood restoration drying, crawl spaces or any environment drying whether inside of outside the home. Commercial quality for reliability and safety and tough for the use in trades applications such as carpet cleaning, paint drying, plaster drying, commercial storage. DH3500 can work in 3 hole mode or 4 hole. 4 hole means it can dry pressure neutrally so can be used in a n enclosed spaces even a commercial freezer to prevent ice build up and save running costs. Can be used in external spaces such as boats, hotels, restaurants, holiday homes and RV s. Optional plug-in humidistat allows remote operation perfect if out of sight or built in with ducted 125mm & 80mm ducts.