The SP 4x4 features a backlit linear meter to monitor input voltage, which gives the user a familiar analog style readout when monitoring voltage from a power source. The SP 4x4 also features ART's 4x4 distribution on the back of the unit - four of the eight rear outputs are 1.25 inches apart. This allows the user to plug in wide power cables and multiple wall wart devices, and still have eight total power outlets to choose from. Built into the SP 4x4 is a surge and spike protection system, designed to protect powered equipment from harmful electric surges and spikes.