The Prospenser bottle-top dispensers deliver safe and precise dispensing of liquids, including strong acids, bases and solvents from a supply bottle. Special features include an easy-to-adjust calibration mechanism and anti-drip precision valve for enhanced accuracy and usability. A fine adjustment mechanism allows for even greater reproducibility for repeat dispensing. Prospensers are fully autoclavable and easy to dismantle for cleaning and maintenance. Wide range of adapters are included to fit most common bottle sizes.