What are these?

[Ericb]

My Grandma passed away a couple years ago. We have found several of these on important key rings. Anyone have any clue what they are? They all have 4 numbers on them and say Knock out.

 

[Davey Crockett]

Are they about the same thickness as a key ? Old keys had knockouts and numbers were the lockset code . Other than that I'm clueless and wondering myself.

 

[Davey Crockett]

 

[Fester]

I am guessing here but could the numbers indicate a key? So for example if you lose a key you could take the code/number to a locksmith and have a key re-cut?

 

[Ericb]

I think that's it! I've found multiple sets. Some more of a cresent and some rectangular like in your pic. Also have a pair with each number.

Any clue did they do this on all keys? Car keys?

 

[Davey Crockett]

GM car keys are the only ones that I'm aware of. Back in the day GM had a rounded key for the doors and square key for the ignition.

 

[Ericb]

Very much appreciated Davey!

I've found a few other relics that I'll share on here another day.

 

[Davey Crockett]

No problem, I enjoyed it. wife and I play "what is it" on youtube.