These had many uses back then. They helped button up boots, hook-up corsets and helped button all those tiny buttons on things back then. This is the second one in my shop. It's a little longer than the other and in slightly better shape.
TRIPLE lamination! Look closely and enlarge the photos. The clear "apple juice" celluloid (NOT Bakelite) on bottom and pearly celluloid on top but there's a skinny layer of white in between to bring out the differences. Hook appears to be steel.
Nowadays? I'm sure there are plenty of uses but this is a great decorative / display item for a vintage or Victorian vanity.
If you see the last photo, you will see it has been added to the vanity. The vanity has been filling up with items already listed. It's ALMOST full. Most of Luna's home items are vintage and antique vanity decor.

This item is sold from an excellent, highly rated vintage boutique in Northfield, OH.