These disposable Pyrex® glass centrifuge tubes are manufactured from Type I borosilicate glass and have GPI threads. They are supplied without caps. The tubes are designed to withstand centrifugation up to 3,000 RCF and are packed in convenient, easy to use packs, which are shrink-sealed for protection during shipment. For reusable phenolic screw caps with white rubber liners, see No. 9999, for reusable phenolic screw caps with Polytetrafluorethylene (PTFE) faced rubber liners see No.