What is it?

[1982fxr]

Looks kinda sorta familiar, bought a toolbox, it came on the key ring...

 

[Slackerzinc]

Other part of a 2 piece key ring. Pushed one end in to separate it
https://www.amazon.com/dp/B000CDIHT6/?tag=atomicindus08-20

 

[jakemac]

It's the disconnected half of a two part keychain.
The full keychain lets you keep the clip on your belt and pull the key off to use.

 

[tvtaurus]

Just a key chain.

 

[1982fxr]

Ahhh ok thanks

 

[wmm2]

Looks kinda sorta familiar, bought a toolbox, it came on the key ring...

Here's what the other half looks like.

 

[avmaine]

We used to use them at the police department. they always broke though.

 

[davethorik]

Whenever i see the HF pass/fail thread, I always forget this. I got one there quite a few years ago, last few times noticed the version they now sell looks like yours. Mine looks just like a quick disconnect air fitting, but smaller. I keep my motorcycle key on it so I don't have my whole keychain sitting on the dash cluster, lol.

 

[BDT/NWMN]

male end of a pneumatic key ring

 

[joe_padavano]

male end of a pneumatic key ring

"Pneumatic"? Is that like an inflatable key ring?

 

[madison069]

They can be handy, I got one that was from the USS company nearby.

I keep the car keys on one side and the house keys on the other side so if someone forgot to get something from the house and we are already in the car I can just give them the house key without turning the car off.