A ring mechanism for retaining loose-leaf pages has supporting hinge plates for pivoting motion relative to a housing to open and close ring members. The mechanism further includes a thin, flat travel bar between the housing and the hinge plates. The travel bar moves relative to the hinge plates between a position blocking the hinge plates against pivoting when the ring members are closed and a position allowing the hinge plates to pivot when it is desired to open the ring members. The travel bar is supported in a generally vertical orientation by the hinge plates within a guide in the housing. The guide controls movement of the travel bar lengthwise of the housing.