These Holographic Diffraction Gratings are highly efficient embossed Holographic Optical Elements (H.O.E.). Diffraction Gratings are used for the direct viewing and analysis of spectra from different gas tubes and other light sources. The quality of the spectrum produced from our gratings is the brightest possible with a minimum of distracting visual noise. Our gratings are the principal component in a spectroscope and are used for experiments pertaining to the study of light and color. Project a spectrum using an overhead projector or 35mm slide projector for spectrum demonstration purposes. Use in conjunction with colored film gels for additive and subtractive color demonstrations.