Precision bore tubing is used these Class A Pyrex® burets to assure accuracy between any two points. The capacity tolerance on these burets is established by ASTM E-287 and is calibrated in accordance with ASTM E542. Each buret is individually serialized and supplied with a Certificate of Identification and Capacity, traceable to NIST standards. Durable colored graduations are sharply defined and easy to read. Carefully ground ST stopcock gives precise control. All sizes furnished with a 2mm bore stopcock plug. For replacement Pyrex® stopcocks, see No. 7680. For replacement retaining clips, see No. 7280. Each buret is supplied with a dust cover.