This Phenolphthalein Indicator solution is manufactured in our USA laboratory by experienced chemists using strict quality control procedures. It is commonly used with acid-base titrations and as a "neutralization" indicator for determining when excess base such as sodium hydroxide or potassium hydroxide is present. Our formulation does NOT contain highly flammable, low-molecular weight alcohols but uses safer propylene glycol thus avoiding the flammability hazard. This 8-pack of small flip-top dropper bottles is perfect for use in classroom lab activities and in research laboratories.