5X GoTaq® Reaction Buffers contain MgCl2 at a concentration of 7.5mM for a final concentration of 1.5mM in the 1X reaction. The 5X Green GoTaq® Reaction Buffer has two dyes (a blue dye and a yellow dye) that separate during electrophoresis to show migration progress. The buffer also includes a compound that increases sample density so that samples can be loaded directly onto gels without the need for loading dye. The blue dye migrates at the same rate as a 3–5kb DNA fragment in a 1% agarose gel. The yellow dye migrates at a rate faster than primers (<50bp) in a 1% agarose gel. The 5X Colorless GoTaq® Reaction Buffer has the same formulation as the 5X Green GoTaq® Reaction Buffer but does not contain dyes and is recommended for any applications where absorbance or fluorescence measurements are necessary prior to PCR cleanup. Both buffers are supplied at pH 8.5.