Scale is permanent brown stain

·         Specially designed rubber washer is supplied with each pipet and is used to support the pipet in the neck of the test bottle

·         Designed from ASTM Specification E1043, Type III (9 mL) and Type III A (18 mL) requirements

·         Manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class A requirements