Large Narrow-Mouth polycarbonate, polypropylene screw closure. Autoclavable, glass-clear bottles with excellent impact resistance. NNI now offers the widest selection of clear polycarbonate bottles from 500-mL and 1000 mL. The 500-mL and 1000-mL sizes are good for smaller volume applications where you need to see your contents. NOTE: Before autoclaving, just set cap or closure on top of the container without engaging the threads. Autoclavable.