Keithley Model 2182A Nanovoltmeter

Features :

    7-1/2 Digits
    1 nV resolution on 10.000000 mV range
    Make low noise measurements at high speeds, typically just 15nV
    p-p noise at 1s response time, 40 to 50nV p-p noise at 60ms
    Delta mode coordinates measurements with a reversing current source at up to 24Hz with 30nV p-p noise (typical) for one reading
    Averages multiple readings for greater noise reduction
    Synchronization to line provides 110dB NMRR and minimizes the effect of AC common-mode currents
    Dual channels support measuring voltage, temperature, or the ratio of an unknown resistance to a reference resistor
    Thermocouple linearization (8 T/C types) and cold junction compensation
    GPIB and RS-232 Interface