The Model 680 Microplate Reader is an eight-channel, vertical pathlength photometer that measures the absorbance of the contents in the wells of a 96-well microtitration plates. It can perform single or dual wavelength measurements and can report absorbance values to three decimal places. The Model 680 reader can be programmed by entering commands through the membrane keypad to define plate reading and data analysis parameters as testing protocols and select report types. Hard copy reports can be produced by an optional on-board thermal printer or external printer. The Model 680 reader can also be controlled by the Windows’ based Microplate Manager software (catalog number 170-9520) program, through its built-in RS232C serial interface device. Microplate Manager software program provides a complete, user-friendly package for protocol programming as well as data analysis, for all absorbance microplate readers from Bio-Rad Laboratories.