Use this module to automatically activate sound modules, animated accessories, as a train detector or as a simple auto reverse controller. DT-1 activates electronics (sold separately) and keep them running for up to one minute. Can be used anywhere on top of the layout, a few inches from the tracks. Fully assembled unit is complete with voltage regulator, timer circuit, timer adjustment, sensitivity adjustment, double pole double throw relay and terminal strips. Measures 1 x 3-13/16 x 1/2" 2.5 x 9.6 x 1.2cm.