What is it?

It is. A rubber airline hose hypodermic pressure gauge. I'm not sure what the wire is for unless it's intended to be left in the hole to seal it.

and that the small hole made by the needle would seal itself

In article , Kevin Steele writes

I'll defer to Dave's knowledge as I have no idea. However, I have been around long enough to remember that hypodermic needles, in the days when they were all steel and were re-usable (after autoclaving, if for medical use) always came in little plastic cases of 6 or 12 with fine brass wire for clearing any blockages in the needle. I still have some of these from time spent in labs in the 60s and 70s, and have occasionally found the brass wire extremely useful, as it is much finer than anything else I have. Mind you I have one huge one which probably could take a smallish brass rod... (Elephant doctoring?)

You hypothesis sounds very iffy to me, I should think it would be a major pain to get the needle back over the wire, and leaving the wire behind might even cause problems. Also quite unnecessary since, as Dave says, thick-walled rubber tubing is pretty good at self-healing. (Actually I doubt it actually heals, it's just that the pressure pushes the walls of the small hole together.)

David

Thinking about it the wire is poddibly just for clearing the needle of any plugs of rubber that might get in there.

Thanks Dave, I thought that seemed a reasonable explanation.

Regards Kev>

For some medical applications, large hypodermic needles are used with a wire core in place to avoid cutting a core (ouch). It could be that the wires are there with these needles for the same reason.

Mike