HO, S, On3, On30, O-Scale Uncoupler Under-the-Track Under the track "hidden" installation. A permanent magnet and steel intensifier plate are included along with instructions. Suitable for a variety of scales from HO to O-Scale. Track not included 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. On some track you may need to trim the bottom of the ties to fit the magnet(s) closer to the rails. Track not Included. Contains: One Delayed Action Magne-Matic® Uncoupler & One steel intensifier plate WARNING: CHOKING HAZARD - Small Parts - Not for children under 14 years. Kadee Quality Products Co. products are not toys and are not intended for children under 14 years old.