12x 2-wire Red/Green Ground Signal _ A pack of 12 x 2-lamp plug and play signals in 4mm scale (OO) supplied with NO control board. The DCD-MGS-RG is a simple design 2-lamp ground signal that was first seen on a limited basis in the 1920 in the UK but it was very widely used internationally. In addition to its world-wide use it is also perhaps the perfect indicator signal for those with large storage or fiddle yards giving a clear Red/Green indication of track access if used for this. Use as add-on for Alpha Mimic control signal systems OR use independently if you wish. Please note: If used with other power sources resistors MUST be added. (we suggest 5000 ohms or 5k resistors). Failed LEDs because of incorrect connection will not be covered by warranty.