- 5361A Agilent Keysight HP Frequency CounterCondition: UsedFrequency: 20 GHz
- 53210A Agilent Keysight HP Frequency CounterCondition: UsedFrequency: 350 MHz
- 5300A Agilent Keysight HP Frequency CounterCondition: UsedFrequency: 50 MHz
- 5328A Agilent Keysight HP Frequency CounterCondition: UsedFrequency: 500 MHz