The two detectors are used to measure sample and reference respectively and simultaneously for optimizing measurement accuracy. Lamp Selection enables conserving the life of D2 & Tungsten lamps. Real time clock for date & time stamping of results. LIGHT PATH DESIGN: DOUBLE BEAM TIUV1900 series double light design can prevent circuit fluctuation and stray light to ensure stability of the instrument. LONG PATH LIGHT DESIGN TIUV 900 series unique 520mm long light path design with greatly improved resolution. 16MM OPTICAL BASE TIUV1900 series use a rigid 16mm diecast aluminium base as their optical mount to ensure the stability and reliability. 6 INCHES LCD DISPLAY TIUV1900 series have a 6 inches LCD display to show results and curves directly on the screen. SOFTWARE FUNCTIONS Multi functions operated directly on the spectrophotometer and display the test results' curve and data: wavelength scanning, standard curve, kinetics, multi wavelength scanning, DNA/protein test. PERFECT CALIBRATION SYSTEM All baseline, wavelength, dark current can be calibrated automatically to keep good running conditions. DATA OUTPUT TIUV1900 series are equipped with USB port to connect with a PC