The "S" Series Cabinet Units add several maintenance and operation features to the already proven E-Series Systems. Automatic back-flush warning, over pressure shutdown, Low voltage shutdown, internal drip tray with float switch shutdown, and remote alarm provisions. Featuring easy to operate and maintain controls and indicators, the S-Series is our most popular System. Like their E-series cousins, the S-Series systems are the same physical size, and have the same power requirements. As the S-series uses the same Electrostatic Cell and water absorber, it has the ability to provide finite fluid filtration for up to one year of continuous operation without maintenance or operator intervention. Imagine ultra clean (ISO 10/7/0) fluid filtration for just 4 CENTS per operating hour cost, and an initial purchase price that's more often than not, less than the cost of the fluid in your reservoir!