Replacement Pads for Rail Tracker™ Use Rescue Pads for semi-annual cleaning to remove heavy build-up.2 replacement pads per package.Works for N, OO/HO and three-rail O scale track. Patent Pending These are replacements for those included in the Woodland Scenics WTT4550 Tidy Track kit. These are abrasive pads for extra cleaning power when maintaining neglected track or track that is in a dusty environment. Ideally, they are used in conjunction with the Rail Tracker in the kit, or could be simply held against the track with your fingers and moved along the track that way. They are more abrasive than the Maintenance Pads, yet remain gentle enough not to damage the track. There are 2 pads in this pack.