These probes are the easier way to put in communication pipeline fluid with the outer environment. If  the fluid flows from the inside to the outside we have “sampling probe”; if the same flows from the outside to the inside then we have an “injection probe”.
Simply speaking the Injection/Sampling Probe is a tube connected from one side to the Injection Nut; the other side is realized following process needing.

Some possibilities are:

“Open End” where the pipeline fluid turbulence disperses injected fluid.

“Quill” where the previous dispersion mechanism is facilitated by the quill cut
 “Atomizing Nozzle” with several possibilities of nozzle conformation due once more to dispersion needing (injection capacity, fluid velocity, angle of dispersion).

Injection/Sampling System consists in: Injection/Sampling Probe, Injection/Sampling Nut, Nipple and Shut-off Valve.

More technical details