Thanks for the welcome and your answer.
The part I show in the photo is 316 stainless steel which is supposed to be for marine applications. You are right, I have to try it but I wanted to post the topic to see if someone knew something. That piece would have two O-rings, one on the inside and one on the outside. The diameter of the pneumatic tube is 4mm but I could use 6mm or 8mm without problem, since if I have a flow problem I use a regulator, the cable I have for example is hard, the material is polyurethane, would it work for WetLink? I see that the engineers say yes, but for air there are other cables such as rubber that could work but I would have to test to what extent it compresses the air flow and if the WetLink seal would work with a hollow cable, well what in the end I understand that I have to try and test and retest, but it would be very interesting to use WetLink for pneumatics apart from electric cables, hopefully the engineers could do a test in water, confirm it, something similar to Cable WetLink . The coincidence that the Swagelok company is near my house and I did not know it, I see that they have very good material, I will also ask and publish the possible combinations.
Thanks for your work.