Check the listing for details. COWIE PTFE Stirrer Bar Plain 65 x 13mm 001.265.13. Condition: New. Listed at 142.49 USD. Virgin grade PTFE conforming to FDA and USP Class VI. General purpose stir bar for a wide variety of applications. More turbulence at lower speeds than cylindrical shape. Shelf life is considered indefinite within the confines of normal use and storage conditions.