| Description/Model | 6415A (High Accuracy Type)  | 6425A (High Voltage Type)  | 
| Digit | Decimal , 7dials | Decimal , 6dials | 
| Resolution | 0.1ppm | 1ppm | 
| Frequency Range | 50Hz to 10kHz | 40Hz to 1kHz | 
| Ratio Accuracy | 0.5ppm(at 1kHz, referred to input) | 1ppm(at 60Hz, referred to input) | 
| Maximum Input Voltage*1 | 0.35V rms/Hz | 5.0V rms/Hz | 
| Input Impedance | Above 100kΩ(at 1kHz) | Above 50kΩ(at 60kHz) | 
| Output Impedance | Below 5Ω | Below 20Ω | 
| Output Current | 1A max | 1A max | 
| Dimensions(W/H/D) | 450 / 130 / 240 (mm) | 450 / 130 / 400 (mm) | 
*1 Voltage 350 V rms MAX