Kimble kimax class-b automatic burets used in general purpose volumetric analysis and for repeated titrations where class b tolerances are appropriate. Both the filling and overflow tubes accept 1/4″ id flexible tubing filled through a self-lubricating, chemically-resistant ptfe stopcock plug easy-to-read durable black ceramic enamel scale ref: astm method d1744 designed from astm specification e287, class b requirements manufactured to the specifications found in astm e694 calibrated to the accuracy requirements found in astm specification e542 manufactured from 33 expansion, low extractable borosilicate glass conforming to usp type i and astm e438, type i, class a requirements. Warning: this product can expose you to chemicals including tetrafluoroethylene, which are known to the state of california to cause cancer. Prop 65 warning