Grease-Free PTFE stirrer bearing designed for use in moderate vacuum applications. Bearing consists of a threaded glass adapter having a 45/50 inner joint, a saddle o-ring, a bushing with compression and locking nut, and a precision PTFE inner bearing. The saddle o-ring provides only glass and PTFE contact with the reaction, while allowing for the vacuum tight seal. Design of the bearing permits replacement of the saddle o-ring at a fraction of the cost of the entire bearing.