Hello, can anyone tell me if PROBEX needles(p3,p4 and p5) be used with the ONE-TOUCH machine.

Most probably not…
The One Touch needle has a much longer and wider shank than the F-Shank, common to most needles. This is to support the retractable feature of the One-Touch. I will post a picture of a One Touch needle versus a typical F-Shank, two-piece needle.
I was not familiar with the Probex products. They seem to have a special needle holder and special needles that include a plastic collar where the shank meets the needle. I did find a picure of Probex needles being dispensed on the web and it appears that they are very similar, it not exactly the same size as F-Shank needles. Even from the small picture it is evident that they are not long enough to fit the One Touch.
If you bought the Probex holder as well as the Probex needles you could easily “hot wire” these to use the current managed from the One Touch, just as you could do this for a standard needle holder and any F-Shank needles. The main feature of the Probex is the need not to steralize any parts of the needle holder between patients. This doesn’t matter to the DIY’er that is the only one using their equipment. Unless you prefer the Probex “ergonomic” holder design there seems no real advantage over a generic F-Shank holder…and it probably costs more.

I hope this info helps, maybe someone with a Probex set-up could verify that the needles are just modified F-Shanks.

ceecee just loaded a helpful photo here:

Hello ceecee,thank you very much for this very helpful information.
I think I understand you to mean that most needles are
f shank, and can only be used with the one-touch if I modify it. The only reason I wanted to buy this type of needle or any other disposable needle,is that it is very easy to buy pro needles on e-bay in the UK, buying replacement one-touch needles is such a bother.

Thank you for taking the time to down load pictures, it was very helpful to see what they look like.