The screw in the visor tightens a clamp that holds the rod that goes thru the length of the visor. I can't recall whether the rod has some nibs on it that orient it within the clamp... I've had mine out and back in.... but as I recall it wasn't quite as straight forward as I'd originally thought. Hands Aus ... on this web-site (Bob in Austrailia) will almost certainly recall and provide direct instructions. He's the one that described the procedure to me when I was removing my visors (to have the brakets rechomed).