Spectrometer is an optical instrument which can be used to determine the wavelength of light as well as the index of refraction of solids and liquids. The instrument is supplied with one prism holder 25mm x 25mm glass prism adjustable collimator tube and telescope. Spectrometer measures approximately 10 tall and 15 wide (at it s widest setting). Both the collimator tube and the telescope measure approximately 6 long. The base of the prism holder measures 3.75 in diameter.