[Test-Equipment] HP 459A HV Probe?

[Barry]

I have an HP 459A that's new to me.  Can someone please explain to me how this is supposed to fit on the DC probe of an HP 410B?  From what I can see, the tube is simply hollow down to a screw that screws into the 12 kilo-megohm resistor.  Nothing appears to be there to capture the probe, make contact, etc.

I'm not finding anything online other than a brief description of it as an accessory to the 410B.  Can anyone enlighten me on this?

Thanks,
Barry - N4BUQ