Three-way PTFE [PS] stopcock, plain top and stopcock fill tube. Filling tube accepts 0.25"" I.D. flexible tubing. The PTFE stopcock has a smooth barrel finish, and a 1:5 [PS] with an airtight fit. Designed to satisfy minimum delivery requirements for ASTM E287 Class A using equipment which is individually calibrated and certified against equipment whose calibration is traceable to the National Institute of Standards and Technology. Each buret is permanently marked with an individual serial number. Stopcocks are designed to comply with ASTM E911. Constructed to minimize fouling by dirt or grease. The tip should be cleaned as part of a regular maintenance program (cleaning wire included). Ordering Information: Serialized burets are shipped in NSTA approved packaging. Supplied with a Certificate of Graduation Accuracy and a micro-wire cleaning tool.