Volume accuracies and capacities are permanently marked in Amber on each pipette. Pipettes are calibrated "to deliver". all pipettes feature treated and tempered tips to reduce chipping and breakage. Class a pipettes meet all the requirements of ASTM E 969-95. Compliance with the cap and other laboratory certifying groups is indicated by the letter "a" near the top of each pipette. All pipettes are calibrated in accordance with ASTM E 542 and meet the accuracy requirements of ASTM E 969; borosilicate glass meets ASTM E 438 for Type I, Class a requirements. Class b pipettes meet the flow time and volume accuracy requirements of ASTM E 969-95 and are marked with a "b" near the top of each pipette. Reusable, Class a and Class b borosilicate glass pipettes meet ASTM requirements.