This add-on set is ideal for the 74924 railroad grade crossings for C Track. It is required for each additional parallel track. Contact track set: 3 straight tracks each 94.2 mm / 3-3/4″. No other connections required. The road section can be adjusted for a spacing of 26 to 61 mm / 1″ to 2-3/8″ (track spacing of 66 to 101 mm / 2-5/8″ to 4″.