The LM-3S-G is a module that you can install into a model train locomotive so the locomotive can be controlled and setup by a Ring Engineering RailPro Controller, such as the HC-2 Handheld Controller with a Color Touch Screen! After the LM-3S-G is installed in a locomotive, you will be able to control the locomotive speed, direction, up to 6 light outputs and sounds! The LM-3S-G has “Direct Radio” (RF transceiver) built inside. The built in RF module allows commands and data to be sent and received to and from the module. You can load a picture of your choice into the LM-3S-G module. Then you will be able to touch the screen of the HC-2 to take control of your locomotive! You can even download new sounds and light effects using the built in Direct Radio!