This product must be purchased with its base unit - Graphtec GL500a 4VF input module, 4 x voltage inputs with isolation, BNC connectors Voltage Ranges: +/- 100 mV to +/- 100 V full-scale Filters: OFF, Line (1.5 Hz), 5, 50, 500 Hz (-3 dB, -6 dB/Q) A/D Converter: 14-bit resolution