side pins

A projecting pin on the side of the binding over which a clasp-strap is fastened, made from a rigid material such as metal, wood, bone, etc. When made of metal they will have a pointed tang at their inner ends driven into the outer surface of a wooden book board, often with a bolster to prevent the projecting side pin from being driven too far into holes drilled into the boards. When made of wood or bone they are usually cylindrical shafts driven into holes drilled into the boards.