The PM55P With built in Optical Limiter is designed for performers who need to monitor their own signal, such as their vocal, with the main mix. The unit has become very popular with drummers who need to mix a click with a monitor signal. And many sound technicians use the PM55P as a quick line tester to troubleshoot audio systems. Operates on either one 9 volt battery or the included PS27s power supply. The PM55P also has an included belt clip. Features: Built in switchable Optical Limiter XLR Mic In & Pass Through Ground lift on XLR signal Stereo/Mono 1/4" Monitor Input 3.5mm and 1/4" Headphone outputs Powered by one 9 volt battery or the included PS27s power supply Lots of output level, it's loud Belt clip is included Specifications: Max Input Level: -20 dB XLR, 40 dB monitor Input Impedance: 600 Ohm Mic, - 22k Ohm Monitor Output Impedance: 10 Ohms Gain: 20 dB 1/4", 50 dB XLR Bandwidth: 50 - 20 kHz S/N Ratio: 90 dB Limit Threshold: 0 dB Current Draw: 70 Mils Nominal Max Output Level: 100 Mil Watts @ 16 Ohm. Power: 9 - 15 VDC Size: 4.5" x 4" x 1.375" Weight: 1 lb (.45 Kg)