Atillo: I have had many of these probes and the other similar.
On ebay BEWARE as it is VERY easy for a probe to be dropped even 5 cm and break the thin ferrite core.
The damage can be invisible but the pulse and response will be bad, and impossible to fix.
Suggest to bid ONLY buy if they are guaranteed new or use 100% working with chance to return.
I have paid $35..65 but perhaps in 1990s..2000s
If ANY physical damages in photos, avoid.
fai attenzione al compratore