With signals becoming faster, and power supply voltages going lower, these active differential probes will allow floating measurements from 100uVolts to as high as 7000 volts. These probes provide high CMRR and a broad frequency range.
The 4200 series has been discontinued and Probe Master is now offering a new line of Differential Probes. Although we do not manufacture Differential probes, we felt there is still a high need for these probes in the US. We will support this new line as we did the 4200 series.