Abstract: A track-guided flexible closure of the sort commonly referred to as a roll-down shutter has a plurality of longitudinally interconnected elongated slats extending between two parallel tracks. The closure may be connected to the tracks by metal retaining members slidable within the associated track. In an improved closure each track is a composite track made up of an external metal track member and a separate polymeric track liner within each metal track member. Each liner acts to prohibit contact between the respective metal track member and any of the retaining members over most of the total length of the track.