This document is the user manual of the spectrophotometer 721 series, which introduces the characteristics of the product, including optical system, display, wavelength range, light source, detection element, spectral bandwidth, stray light, wavelength accuracy, wavelength repeatability, transmittance accuracy, transmittance repeatability, stability, transmittance measurement range, absorbance measurement range, concentration direct reading, RS232 communication port, printer, software support, power supply, external shape Dimensions etc.