The Pyrex® Pear-shaped Graduated Centrifuge Tube, Goetz from Corning are round bottom tube made from borosilicate glass. Non-sterile. The lower stem is graduated upward to 1 mL in 0.05 mL divisions. The body is graduated from 1 mL to 5 mL in 1 mL divisions; from 5 mL to 50 mL in 5 mL divisions; and from 50 mL to 100 mL in 10 mL divisions.