Using the advanced Czerny-Turner monochromator design with optimization of the optical system, baseline change due to refractive index is minimized. Baseline fluctuation from changes in environmental temperature is reduced with a temperature-controlled cell, baseline drift caused by temperature fluctuation in the light source is also reduced with a temperature controlled light source. The result is excellent stability with the noise level +/- 0.2x10-5 AU and drift 1x10-4 AU/h. Both detectors offer simultaneous dual-wavelength data acquisition and spectral scanning. User maintenance can be done without removing the module from the system. Front panel access is used for light source replacement and automatic wavelength calibration can be carried out using a mercury lamp. Both detector s include high speed data acquisition at up to 100 Hz and can be used for conventional HPLC with the standard flow cell and for UHPLC/RHPLC when used with the SP type semi-micro cell.