Help me identify this needle!

Several months back I stopped into Goodwill and found several pairs of these needles there. These needles are all single needles with the plastic cord and a plastic disc attached at the end and they have the ‘Boye’ name on it. I have these in several sizes but I have NO IDEA what they are called and what they are even used for. I’ve tried searching but can’t find anything. Can someone help me? They were too good of a deal to pass up even though I have no idea what to use them for. The picture of the needle is here:

Knitting Needle

Any help will be appreciated!

It’s a flexible straight needle. I have several from back in the 70’s when I first started knitting. You can still buy them new now; I’ve seen them in places like JoAnns, AC Moore, etc.

You use them like any straight needles, they just hold bunches more stitches like a circular needle will.

When I first started knitting a few years ago I bought a bamboo one. It’s just a straight needle. I didn’t care for it though.

Thank you both for helping me! I had no clue what you used them for or if they were for something special. LOL I had never seen those before. Of course i’m relatively new to knitting.