This Bromothymol Blue Indicator 0.04% (w/v) solution is manufactured by qualified and experienced chemists in our USA laboratory using strict quality control procedures. This product is commonly used as a pH indicator which shows a yellow color at pH 6.0 and a blue color at pH 7.6. This product may also be used in other applications. Included in the package is an empty 2 oz dropper bottle and a convenient dispensing cap to refill the dropper bottle. NOT FOR HUMAN CONSUMPTION.