Stir bars are coated with PTFE covering, built-in pivot axle helps to reduce vibration and wear during stirring How to use: you can place inside a container of liquid or solution that is seated on a magnetic stirrer, and use a rotating magnet or multiple stationary electromagnets to create a rotating magnetic field Wide application: the stir plate magnet bar can work well with types of magnetic stirrers or heating stirrers, and is often applied to stir a liquid or solution in scientific research, universities and laboratories Features: the laboratory bar has acid and stability as well as organic solvent tolerance, and is almost insoluble in solvents; The maximum temperature is 250 degrees centigrade and the minimum temperature is -196 degrees centigrade Quality material: the rod magnetic mixer is made of quality PTFE, and its cylindrical shape and smooth reduce friction and improve smooth rotation, nice for laboratory Colour: White Material: PTFE Size: 5 x 10mm/6 x 12mm/8 x 20mm/7 x 25mm/8 x 28mm/8 x 30mm/9 x 35mm Package Contents: 21 x rod magnetic mixer Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.