Help Identifying Collets (SSC1)

[Flash Gordon]

These were included in a lot that I purchased at an auction.
I have about 22 of them.
I think they might be used in a milling chuck of some kind.
Does anyone have any info on these.
Thanks!

 

[SeikiCorp]

Used in 1 1/4 milling chucks and hydraulic holders.
They don't have any real 'collapse' and need tight tolerance tool shanks. +0 -.0003 max.