It adopts visual aiming and manual measurement method, which is easy to use.   Measurement mode: optical rotation Light source: sodium light + color filter, wavelength 589.44nm Measuring range: ±180° Scale value: 1° Dial cursor reading value: 0.05° Magnifier magnification: 4× Test tube: 200mm, 100mm Power supply: 220V±22V, 50Hz±1Hz Instrument size: 540mm×220mm×380mm Instrument quality: 5kg