The Prospenser bottle-top dispenser can safely and accurately dispense liquids, including strong acids, strong bases and solvents from a liquid supply bottle. The easy-to-adjust calibration mechanism and anti-drip precision valve improve accuracy and usability. Prospensers are fully autoclavable and easy to dismantle for cleaning and maintenance. Fully autoclavable at 121C, 2 bar for 20 minutes. A variety of adapters are included to fit the most common bottle sizes. All models are equipped with an anti-drip safety valve or closed cap, which can prevent dripping when the bottle top dispenser is not used. The fine adjustment mechanism can achieve higher repeatability of repeated distribution.