Kimble kimax class-b burets used in general purpose volumetric analysis and titrations where class b tolerances are appropriate. Funnel fill style buret replacement 2 mm straight bore ptfe stopcock plug is 821001-0002 easy-to-read durable black ceramic enamel scale ref: astm method d974 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