Egg-shaped stir bars have oval magnets—ideal for use in round-bottom flasks. Shape conforms to flask bottom and ensures complete mixing. Super-strong Alnico V magnets remain coupled to drive magnets—resisting spin out at high stirring speeds. . One-piece coating of PTFE resists corrosion, heat, and cold. . Chemically inert stir bars won. . Low-friction PTFE coating ensures smooth spinning and maximum energy transfer.