400 MHz, ±2 kV, Switchable Attenuation, Differential Active Oscilloscope Probe—The DA400B is a high-voltage differential, active probe that offers 400 MHz of input bandwidth and switchable attenuation between 50x, 100x, 250x, and 500x. You can use it with oscilloscopes that provide 50 Ω input impedance. The probe requires an external power supply.