Not sure if this is the correct thread for this. I have been looking for Notos fill probe o rings. I wanted to buy local. Today at Ace hardware I found these #61 o rings and visually they looked close. So I bought them. I lubed them up with silicon gel and pressed them on. And they worked!! Filled my air cylinder to 3400 psi. I hope this helps you out. I have not seen these o rings mentioned on here.
