These Pyrex® burets are suitable for use in school and institutional laboratories not requiring the accuracy of our Class A models. They are used when dispensing large volumes of liquids rapidly and accurately. Made from close tolerance, accurate bore tubing with uniform walls, these burets have a permanently colored scale. Tips are carefully drawn and ground to reduce chipping. Provided with a PTFE stopcock plug to reduce freezing and eliminate lubricant contamination. The smooth micro-finish of the stopcock barrel assures a precision fit and optimum leak-resistant performance. For replacement stopcock plug only, see No. 1-7681.