These units are ideal for tight rack applications where no space exists for more traditional cooling products.  Even if there is space, these are great for directly cooling components in open 2 or 4-rail rack applications. The units easily attach to the side of the rails and can be positioned where cooling is needed the most. The fans can also be easily reversed so you can direct air to blow directly over the components or pull hot air away from the equipment. In 4-rail racks, the units can be either mounted to the front or back rail and they can be perfectly positioned to precisely cool even the hottest running components. The 2 Fan version is perfect for smaller components and is priced where multiple units can be utilized in a full rack system. These units are affordably priced but feature the highest quality fans that were designed for extended use and are ideal for vertical mounting (traditional bearing fans are not intended for vertical mounting). Not only are the fans specially manufactured to be quiet and do not create electrical noise due their design, the fans are mounted using specialty hardware that absorbs normal fan vibrations which further reduces noise. As with all of our products, the fans are variable speed and, by adding a Temperature Controller, you can add automatic control including basic on/off as well as automated variable speed control. These units are compatible with all of our Temperature Controllers and the controllers simply plug inline between the power supplies and fan units.