US Patent 7124479 Snap hook

A hook and an eye are integral with and located at opposite longitudinal ends of a body. The hook includes a tip spaced from the body and defining a mouth for attachment of the hook to a ring or other object. A lock pin mounted in the body moves axially between a closed position engaging the tip of the hook and an open position. The body has a flat, easily gripped shape with a button at one side movable in a transverse direction. A cam system translates transverse button movement into axial movement of the lock pin, and provides a decreasing force-displacement characteristic. The hook is designed to break to prevent user injury in the event of excessive force, and includes a ramp surface facilitating detachment of the hook.