What is this?
 

Can anyone tell me what this is? It was found with my mother's sewing things. The center comes out like an embroidery hoop and the bottom part slides...

Little hoop for your sewing machine. The metal end goes in a hole on your machine table and it is able to slide in and out a bit to accommodate whatever you are darning/embroidering in the hoop.

Squeeze the metal pieces together to remove the clamp that holds the fabric in the hoop.

It looks just like the one that came with my Bernina Record 830 from the 1970's.

I'm totally amazed at how fast questions such as this one can be answered on The Quilting Board. I never would have known what it was in a million years. Way to go!

My Bernina 830 has one like that .it came with the nachine. I biught the machine in 1982.

Thank you!! I don't know that I would have ever figured that out!

You are welcome. I just happened to have the machine those came on, so I knew what it was. It's a bit obsolete, what with all the new bells and whistles that come on more modern machines.

They are also used to darn socks.

Yup. I was told it was a darning hoop. I have one somewhere for my Bernina. It's never been used, of course, since I don't darn anything.