HO, S, On3, On30, O-Scale uncoupler, under-the-track. O-Scale: Because of the thicker ties and higher rail in O-scale it will be necessary to use 2 or 3 magnets stacked together and one steel intensifier plate on the bottom of the stack. Track not included. Contains: One delayed action Magne-Matic(R) uncoupler and one steel intensifier plate.