Our Rare Earth Egg Shaped Magnets are coated with a Teflon finish coating allowing for no reaction to fluids and allows the magnet to withstand high temperatures of 280°C.These Egg shaped stir bars are meant to be used with your heating mantles. The egg shape bar is best used for a round bottom flask because the spin is unrestricted by the vessel contour.ModelMantle SizeREE-9x24500 ML / 1LREE-12x352L / 5LREE-20x6412L / 22L For Technical Support, Questions, or Other Issues Please Email or Call Us!