Stir bars, also known as magnetic stir bars or spin bars, are commonly used in laboratories to stir or mix solutions. They are small, cylindrical or oval-shaped bars made of magnetic materials, such as Teflon or glass, that can be magnetically rotated inside a liquid solution by a magnetic stirrer.
The use of stir bars is preferred over manual stirring as it provides a more uniform and consistent mixing of solutions. Stir bars are available in different sizes and shapes to suit a variety of applications, and can be coated with materials like PTFE or silicone to prevent reaction with the solution being stirred.