When positioning a patient on the operating table, the bean bag is moulded around them: a special suction line is then attached to a valve in the bag, extracting all the air and creating a vacuum. This forces the beads together, fixing the bag into the exact moulded shape, keeping the patient securely positioned for the duration of the procedure. After surgery, the valve is opened and the Bean Bag Positioner becomes soft again, releasing the patient and ready for reuse.