Pyrex® Sofnol pattern automatic zero burettes from Scilabware conform to ISO385. For water testing. Graduations are in blue enamel. With GP rotaflo stopcock offering fine drop control when dispensing. The burette is filled by squeezing the accessory polythene bottle. Once the bottle is released, excess liquid can drain back into the bottle until the burette is set to zero. Requires, but is not supplied with, BW597-34 reservoir.