Protect motorists along your HO Scale railroad with the SceneMaster Grade Crossing Signal Controller. Designed to provide a realistic flashing rate with all SceneMaster Crossing Signals (each sold separately) the unit comes fully assembled and ready to use on DC-powered layouts*. Additonal features include: Controls up to 4 signals Includes 4 optical sensors Fully assembled control unit ready to use on DC layouts Simple plug-in wiring connections Operates on 18 volt AC from power pack accessory terminals Complete installation and hook up instructions included *PLEASE NOTE: This unit is only for use on DC layouts - DCC systems can damage the controller. Check out the full selection of SceneMaster and Cornerstone Crossing acessories here!