Grass Instruments Polygraph DC Driver Amplifier 7DAG, Pre-Amplifier 7P5B AS IS

Grass Instruments Polygraph DC Driver Amplifier 7DAE W/ Pre-Amplifier 7P1J

Grass Instruments Amplifier / Data Adapter Cable Model P511

GRASS Instruments Polygraph Low Level DC Pre-Amplifier 7P1G UNTESTED

Grass 7DAH Polygraph DC Driver Amplifier 7P8H Sphygmomanometer EKG-Pulse Pre Amp

Vintage Grass Instruments Model 8A5 (Untested)

GRASS Instruments Polygraph Low Level DC Pre-Amplifier 7P1J UNTESTED

Grass Instruments Polygraph DC Driver Amplifier 7DAL, Pre-Amplifier 7P1K AS IS