There is confusion as to how this product works. This is a "uniaxial" diffraction grating, meaning you see a point light source. and you see an iridescent "smearing" of the color spectrum produced by that light appearing to both the left and right of the point source. Hence the name "linear" diffraction grating because everything is a flat line. However, you NEED to hold it VERY close to your eye (about an inch or so) and you probably still need to be looking in one direction to see the spectrum. This is just the physical workings of prisms, not a defect of the product. Another caveat. Do not touch the film with your fingers (or anything else that can leave greasy marks). The gratings are basically 1,000 tiny prisms for every inch. When you touch the film, the oil from your fingerprints fills the gaps between each microprism, preventing the light from refracting properly. I use them to explain spectroscopy in scientific papers. In my case, I start with a regular tungsten filament incandescent bulb, but then move on to using gas tubes with different gas elements (hydrogen, helium, etc.)