BorosilÂ® Boroflo Burettes offer accuracy, reliability and durability attributable to the highest quality bore tubing to provide uniform and precise graduations. Each burette is individually calibrated by an automated calibration process and has a Boroflo GP (General Purpose) Screw thread with PTFE keys that are highly resistant to chemical attack. Standardly used in the Titration process, flow/drop control and ease of use helps ensure consistent performance. The fluid pathway is made entirely of glass and PTFE, creating a no lubrication necessary, leakproof seal. These Burettes come with no springs or retaining devices, making for an easy dismantling and cleaning process. Glass Quality Grade per Class B of IS 1997:2008/ EN ISO 385.