The performance of this ultra-low cost spectroscope is comparable with instruments typically costing much more. It uses a CD or DVD as a reflective diffraction grating and clearly shows Fraunhofer lines in the spectrum arising from natural light - and distinctive emission bands from artificial sources such as sodium lamps.Differences between fluorescent lighting tubes - e.g. white light or 'warm' light types - can be easily identified by their distinctive emission bands.The spectroscope is made from virtually indestructible polypropylene and supplied in flat pack form - taking about 30 seconds to assemble. It comes with a free CD but can be used with any CD (or a DVD for higher resolution).