Industrial & Scientific" /> Immediate visualization of flow; barbed tube ends Brightly colored polypropylene paddle wheel spins when gas or liquid flows through a system Molded clear polystyrene body with smooth connecting barbs for easy installation Internal flow channel diameter is 5mm, paddle wheel shell is 25mm, overall length is 51mm Not for use with corrosive chemicals or fluids with a temperature in excess of 64 degree C (147 degree F)