PYREX®, borosilicate glass.

These conical centrifuge tubes have white enamel graduations for durability. The 15 ml size is graduated upward from the tip in 0.1 ml divisions. The 50 ml size is graduated upward from tip to 10 ml in 0.5 ml divisions, and from 10 to 50 ml in 1 ml divisions. The phenolic 15-415 GPI threaded screw cap is fabricated of a resin which is specially formulated to resist the effects of temperature and steam. Caps have a glued-in, white rubber liner. The pennyhead stopper is solid.