One of the reviews on that page mention implementing a spectrometer:

> The 1,000 lines/mm Diffraction Grating Plastic Film was used to make a high resolution optical spectrometer. First, the film was removed from its paper 2" x 2" card stock. The crystal clear film was next glued to an optical ring that was mounted in front of a very inexpensive 1,920 x 1,080 pixel webcam. The modified webcam was placed in the back oRead more about review stating Using the 1,000 line/mm Diffraction Grating in a Spectrometerf a pinhole camera-box and mounted at an incident-angle to the incoming light beam. In this configuration different light sources could be introduced to the new spectrometer and their light spectrum captured using a USB-computer input. Thus, a wide variety of light sources could be fully analyzed at a resolution of about +/- 2nm. Using this very inexpensive (1,000 lines/mm) grating, coupled with an equally inexpensive webcam, a high resolution optical spectrometer could be built for under $25.00