Although I know what it is, I though some of the younger crowd might not. I had never seen this Walden item before, although I collect Walden. The first picture is in its operating mode, the socket is 9/16" and there are two, so if you wear one out you can use the other side. Inside is a screwdriver and it is held in the socket by a ball but can be moved up and down and turned. Second picture shows the screwdriver removed.