Curtain pin hooks for curtains without heading tape.
Generally these are used on pleated curtains which have a buckram heading, though they can be used more generally and are sometimes used to close the gap between the curtain and the wall.
Two sizes are available, which I term:
The small pin hooks are suitable for lightweight curtains. Both sizes are made from stainless steel, and this small size is suitable for installations on boats and ships. By far the most popular size is the standard.
NOTE sold in quantities of 1, photo for illustration.