The company states that it is the first sealed, outdoor-rated MPPT charge controller. OutBack Power states the FLEXmax Extreme is said to have a passively cooled design and is the first charge controller to offer full power output over a wide range of temperatures with a sealed unit capable of protecting circuit boards and other sensitive components from dust, dirt, insects and other contaminants. FLEXmax Extremes thermal engineering provides full power output from -20 to 45 degrees Celsius without requiring a cooling fan. By eliminating the cooling fan in the design, the FLEXmax Extreme removes the obstacle to long service life and high reliability, since fan problems can severely limit power output. Additional points include increased wire-bending space and oversized terminals for easy installation with large gauge wire among others.