These 15mL PYREX® conical centrifuge tubes have white enamel graduations for durability. The 15mL size is graduated upward from the tip in 0.1mL divisions. The 50mL size is graduated upward from tip to 10mL in 0.5mL divisions, and from 10 to 50mL in 1mL 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.