The probe is the contact medium for electrical testing and is a high-end precision electronic hardware component.
The main types of probes are: cantilever probes and vertical probes.
Cantilever probe: Blade Type and Epoxy Type
Vertical probe: Vertical Type
1.ICT probes (ICT series Probes)
The general diameter is between 2.54mm-1.27mm, there are industry standard called 100mil, 75mil, 50mil, and the more special diameter is only 0.19mm, mainly used for online circuit testing and functional testing. Also known as ICT test and FCT test. It is also a kind of probe that is used more frequently.
2. Interface Probes
Non-standard probes are typically made for a small number of customers who make large test benches, such as Teradyne and Agilent. Used to test the contact points and faces of the machine and the test fixture.

No	Overall Length/Travel (mm)	Minimum Test Gap (mm)	Diameter of Needle TUBXe (mm)	Spring Pressure (g)
UBX039	33.27	1.00	0.61	0.9
UBX040	35.9	1.00	0.61	1.0
UBX050	43.18	1.27	0.78	(1.5)2.0(2.8)
UBXS050	34.59	1.27	0.77	1.2(1.6)
UBX075	33.1	1.91	1.02	(1.5)2.0(2.8)
UBX100	33.3	2.54	1.37	(1.5)2.0(2.5)(3.0)
UBX125	33.0	3.18	2.02	1.8
UBX156	33.85	3.96	2.36	2.0
UBX169	33.85	4.30	2.68	2.0
UBX189	36.5	4.80	3.16	4.5
UBXQ039	33.27	1.00	0.80	0.9
UBXQ075	33.02	1.91	1.02	(1.5)2.0(2.8)
UBXQ100	33.27	2.54	1.37	(2.0)2.5(3.0)
UBXQL075	36.83	1.91	1.02	(2.0)2.8
UBXQL100	37.08	2.54	1.37	2.0(3.0)
UBXQS050	34.59	1.27	0.77	1.2(1.6)