Ithey are also called CSM - circular sock machine - one are well over 100 years old and there is one company who makes a modern one - they have a cam with a lot of needles that have a latch at the top - the needles go up and down catching the yarn - knitting a tube that comes out the bottom of the machine when you turn the handle - you can get them on eBay for anywhere from $200 (usually need parts or work) up to a normal of around $1000. There is a steep learning curve but you can usually get instructions and u Tube is very helpful. I can make you a pair of socks if you would like!