BK Precision PR-55 50 MHz 10kV High-Voltage Oscilloscope Probe.
If the voltages you need to measure on your oscilloscope are above the specifications of the general purpose probe, B+K Precision has higher voltage probes for you. X1000 Attenuation 100 Mohms / 1 pF Input Impedance 40 MHz Bandwidth 80" (2.0m) Cable Length.