Beaker has easy-to-read, silk-screened graduations; size code; resin code; maximum use temperature; and "no flame" symbol for easy identification by students Polymethylpentene beakers provide a glass-like clarity along with excellent chemical resistance and remarkable heat tolerance Plastic beakers are not intended for use on hot plates but these can withstand autoclaving 250 mL. Nalgene Griffin Beaker, Low Form. Beaker has easy-to-read, silk-screened graduations; size code; resin code; maximum use temperature; and no flame symbol for easy identification by students. Polymethylpentene (PMP). Polymethylpentene provides a glass-like clarity along with excellent chemical resistance and remarkable heat tolerance. Plastic beaker is not intended for use on hot plates, but plastic beaker can withstand autoclaving. Beaker meets the ISO/DIS 7056 International Standards for laboratory plasticware beakers. 250 mL.