This is a standalone device that may be used to control signals or accessory of 2 Amps draw or less. Higher currents can be accommodated with the addition of a relay board sold elsewhere on this site. The controller actuation may be from switch machine, grounded signal (AC or DC), logic signal, or other input. Not sure of your application? Just contact us and describe what you are trying to do. The controller has two variants to support just a DPDT 2 amp relay or also to include direct drive of two LEDs as may be used for indication or signals. It may be used for most gauges of model railroads. This is the same controller as described for use with the DZ-2500 switch machines, but without the additional options.