This invention provides for a component forming a part of a breathing tube, or forming the breathing tube, for example as a part of a breathing circuit for respiratory therapy. The component comprising a tubular body having a foamed wall. The foamed wall can be formed from extrusion of a single extrudate. The foamed wall is of a sufficient minimum optical transparency such that, in use, there is enabled the visual detection of a liquid (or condensate that may have formed) within the tubular body.