These glass-clear tall-form cylinders are calibrated “to contain” and are Class A per DIN 12681 and ISO 6706. Hexagonal base provides stability. Supplied certificate includes mean test value and lot (lot and year are imprinted on product). Thermal stress up to 121°C (autoclaving) does not cause permanent exceeding of the tolerance limits. However, to preserve markings (cat. no. V64604 – V65304), cleaning at no higher than 60°C is recommended. For autoclaving, the design with raised graduations (cat. no. V64614 – V65414) is recommended.