The signal box has optical sensors built-in and has a sensitivity adjustment. Just apply power and put them next to the track. These sensors will do the rest. They have separate inputs and outputs so they can be daisy chained. They have two outputs, which are complimentary, so they can directly operate other signals using LEDs like the MTH cantilever signal. Signals using lamps or solenoids will require the DZ-1075 or DZ-1075M sensors.Click here to see the DZ-1070 Instructions (PDF)THIS ITEM IS CURRENTLY BACKORDERED BY THE MANUFACTURER. Your credit card NOT be charged until it ships to you.