Came across this in the course of a post Christmas workshop tidy up. All I know is that it came in box of rivets etc from an elderly gent’s shed clearance in about 1980.
It’s made of iron or steel and appears to have been formed by hammering or forging from bar or rod.
Its commonly called A ‘Grape Eye’ and can come in different shapes,used for climbing plants on walls by hammering them in the cement joints.
The modern version is made from flat steel with a hole in the top