Unused and a real beauty. Heavy duty high quality rugged metal construction throughout. Consists of a telescope with eyepiece and 21mm clear diameter achromatic focusing objective lens, and a collimator with removable adjustable slit and achromatic focusing 21mm clear diameter objective. The 7-1/2"diameter graduated circle has lines for each degree and is numbered at every 10 degrees. Telescope and collimator are each 8" long. Center table is designed to hold either a prism or grating. Vernier control and scale for precision measurement. Telescope and table rotate about a vertical axis. Spectrometers are used to measure and/or observe spectrum, absorption bands, angles of refraction and reflection, etc. The slit and collimator produce a parallel beam of light which then falls on your prism or grating. The resulting spectrum is then observed through the telescope.