The capacity tolerance on these Class A Pyrex® burets is established by ASTM E-287 and is calibrated in accordance with ASTM E-542 and D-511. Each buret is individually serialized and supplied with a Certificate of Identification and Capacity, traceable to NIST standards. Tips are carefully drawn from accurate bore tubing to insure proper drainage rates. This buret has colored markings, fine, sharp lines and large easy-to-read numbers. The stopcock barrel has a smooth micro-finish to assure leak-resistant performance. Each buret is supplied with a dust cover. All sizes are furnished with a 2mm bore PS PTFE stopcock plug. For a replacement stopcock plug only, see Cat.No. 1-7681-2.