... with built-in lithium battery for 3-4 hours working, Software is easy operating, ... for Portable EMGEP System:Amplifier:Channels: 2/4; Dual-fiber signal transmission isolationSensitivity:0.05μV/div -20 ... mV/div,Amplitude-frequency characteristic: 1Hz~5kHz,Noise: ≤0.4 ... , 16*12, 8*6, 4*4.c) Vision: full vision, half-field (left), 1 / 4 view (I, II, III ...