Jewelry Term...slightly off topic

[fredi*frogi]

This is slightly off topic since its new and not vintage, but I'm at a loss...

I finally decided to switch out my endless hoops for some sparkley stud earrings, and I found ones with balls for backs (like bar bells, but only one end has the ball...). thought they would be more comfortable than the traditional style and they are, I can leave these in overnite just like the hoops...

And, of course, I've lost one of the ball backs. Boo. However, I can't for the life of me figure out what they are actually called, just the screw on ball, to order some replacements! Can anyone help with this term? What's the right word I'm looking for??? 

They are 18 g I've found 14/16 but no 18...all I get when I search for 18 g ball earring back replacement is more earrings. I've tried a number of combinations of those words and nothing comes up!! 

TIA 🙂

Here's a couple of pics so you know what I'm talking about!

Just the ball is all I've lost!

[magpie-market18]

I've always called them ball screw backs.  I googled "replacement ball screw back" and there were quite a few choices.  It looks like industrial stuff pulls up too, but there were quite a few jewelry choices as well.

[ifmelfalls]

A lot of body jewelry uses that kind of screw back. Maybe try searching in that realm of things. 

[fredi*frogi]

ooooo screw backs? Why didn't I think of that!?! LMAO

Thanks so much, off to see if I can find them in 18 g!

[fredi*frogi]

Found some to replace, tho I haven't purchased yet. The set of replacement balls (24) is almost as costly as these earrings were, and since there were 12 pairs in the set, I might not worry about it until I lose more backs (which I hope I don't!)