These needles are the latest way to knit socks. Using 3 flexible 21cm circular needles brings a new feeling to sock knitting. The needles don't get tangled and you won't drop stitches as the needles won't fall out.
Now even the smallest diameters can be knitted very easily. When knitting in rounds, the stitches are distributed over two needles and the third needle is used for knitting - meaning only two needle changes per row.
Short row heels are a breeze on these, just split your stitches with half on each of 2 needles. You can knit heel flaps by placing one third of the stitches on one needle and the rest on the other.
For a short tutorial on using these needles click here