These are needles for machine knitting I got with an old Brother knitting machine. the machine itself did not have anything else – just the needles.
I polished the needles and tested them on my fully functional KH551 – they worked great!!
The needles came from the KH710 but they could be used on KH531, KH552, KH558, KH585, KH588, KH710 and KH800 machines according to this chart: