This egg-shaped Spinbar® Magnetic Stirring Bar provides its own pivot point without a separate ring or abrupt change in contour. Designed especially for use in round-bottom vessels, it spins unrestricted by the vessel contour. Most sizes have egg-shaped magnets. The two smallest sizes have cylindrical magnets with egg-shaped PTFE coating. All Spinbar® Magnetic Stirring Bars are packaged 50/case unless otherwise noted.