The Tektronix P410 is a 10x passive voltage probe. Maximum voltage is 600 V peak-to-peak. It connects to the scope with a UHF connector.
The P410 was Introduced in 1955 along with the Type 541 and Type 545 scopes because at 30MHz the P510A's 50-ohm coax cable exhibited unacceptable ringing due to the impedance mismatch at the scope's 1 MΩ input. The P410 uses a special cable with a very thin, high-resistance center conductor which creates a better impedance match. All high-impedance probes subsequent to this use this kind of cable.