PYREX® Disposable Glass Serological Pipet, Individually Wrapped are calibrated "to deliver" with blow-out and offer long, slender, tapered tips to make pipetting go faster and easier. All pipets have negative graduations and fire-polished tips for burr-free, even flow rates. Easy-open Steri-View™ wrappers (one side paper, one side plastic) have color-coded sizes printed directly on the paper for easy identification by size. Colors conform to I.S.O. standards. Reference: ASTM E-714. WARNING: Do not pipet by mouth, we suggest using a mechanical pipetting device.