The SX21 is a 24dB/Octave two-way frequency divider intended for small sound reinforcement applications. It has Input- Low and High Output jacks- and Input- Crossover Frequency- Low and High Output controls. It is powered by an included 12 to 16 volt DC adapter.24 dB/Octave rolloff.Mono 2-Way crossover.50Hz - 2.5kHz range.1/4- unbalanced Input and Outputs.External power supply for low noise operation.Specifications:Input Impedance: 10K Ohms.Output Impedance: 1K Ohms.Headroom: +10 dBV.Power Requrements: 12 - 16 VDC 150 mA (Rolls part number PS27).Size: 4.25- x 3.625- x 1.5-.