Nalgene DS3131 Sealing Cap Assemblies for Oak Ridge Centrifuge Tubes and Bottles. Autoclavable assemblies seal Nalgene Oak Ridge centrifuge tubes and bottles made of PTFE FEP. For use at recommended maximum speeds (10,000 x g or greater) without leakage, even when full. Also recommended for spinning hazardous materials compatible with centrifuge tube material. Polypropylene screw closure, ETFE, ETFE plug, Viton* fluoroelastomer O-ring. DS3131-0038 features shoulder support ring to prevent shifting, binding or collapse of bottle neck.