Hello Wombat, I know exactly what you are looking for, and the needle threader for embroidery needles is by Lo Ran and this is a flat piece of metal with a larger flat hook one end for thicker threads, and a small flat hook the other end for embroidery floss and for fitting in the embroidery needle eye, the whole thing is about 5cm long. I have a few scattered around which is so useful, and I still have one piece of card that it came on. This was called Needleworker's Accessory Kit and consisted of a needle threader, a magnetic needle minder, and a magnetic needle case, there is also a price still on and this was £3.95, but it is years old. I do remember buying some of these and they were just the needle threader - nothing else.
I keep one handy in my sewing cabinet and use this needle threader when I am finishing off overlocker threads and pulling these through the sewn overlock stitches as there are usually three threads that need to be threaded through a larger needle eye.