KA3 Keep Alive w/Wire Harness -- 1.02 x .45 x .347" 25.9 x 11.43 x 8.81mmTCS Keep Alive (KA) devices are used to supply power to decoders during times of power interruption due to dirty track or problematic track work. The KA3 will power an HO Scale locomotive with headlights on for approximately 6 to 20 seconds (depending on the locomotive and the efficiency of the motor). This Keep Alive includes a Blue and a Black w White Stripe wire to attach it to a decoder.