Water nipple - Do you know how to prevent the metal bits popping out?

[Mek]

Hey does anyone have a picture of what they have in their water nipples that prevent the metal bits popping out?

 

[MobyQuail]

I ordered but did not use the metal ones for that reason, but you may be able to bend a small piece of wire into a U and push it down on the inside until it catches and hold, I was able to do it, but again, I liked the orange ones better, I ordered 12 of each.