These heavy duty round PYREX® bottles are manufactured from low actinic glass for use when storing or transporting light sensitive materials. They include a linerless, one-piece autoclavable orange polypropylene plug seal caps with drip-free pouring rings. New glass bead indicates full capacity line on 100mL through 2 liter size. Bottles have permanent white enamel graduations and marking spots. Caution: Bottles larger than 2L should NOT be used with bottle top filter units, or in other applications involving vacuum pressure, as breakage may occur.