The Bel-Art Scienceware Spinstar star-shaped stir bar has a white Teflon (PTFE) casing and an internal magnet made from alnico V (an alloy of aluminum, nickel, iron, and cobalt) for laboratory stirring applications. The star shape with four rectangular arms and a solid, flat circular center (also called a beaker stir bar) fills the inside diameter of a beaker to create a vortex to the bottom of the container at slow or moderate speeds. The magnet sits inside a Teflon (polytetrafluoroethylene, or PTFE) casing, which is chemically inert, can be used with corrosive chemicals, and helps reduce friction and wear while spinning. The casing material is FDA approved for use in food, drug, and cosmetic applications.

Magnetic stir bars (sometimes called stirring bars, spin bars, or fleas) are used to stir a liquid or solution in biological, chemical, medical, and research laboratory applications. The stir bar is placed inside a container of liquid or solution that is seated on a magnetic stirrer (also called a magnetic mixer), which is a laboratory device that creates a rotating magnetic field using a rotating magnet or multiple stationary electromagnets. The rotating magnetic field causes the bar to spin, which stirs the liquid or solution. Stirring bars are offered in a variety of sizes and shapes, and they are encased in materials such as glass or plastic to help prevent contamination of the liquid or solution, to reduce friction, and to provide resistance to chemicals, abrasion, and heat. The bar may have a pivot ring or pivot point to minimize contact with the container, reduce friction, and improve its spinning. The size and shape of the container and the volume and viscosity of the liquid or solution to be stirred determine which stir bar shape, size, and casing will suit a particular application.

Bel-Art Products manufactures scientific products, including labware, testing equipment, and safety supplies, under the Bel-Art and Scienceware brands. The company, founded in 1946, is headquartered in Wayne, NJ.