The Taylor SpeedStir is a magnetic stirring device that mixes your pool tests by spinning a magnetic stir bar with the push of a button. A second button illuminates the bottom of your testing cylinder with LED light, improving visibility for color changes. Fits all industry standard pool testing and mixing tubes (25-32mm diameter), and is 100% compatible with all TFTestkits cylinders. Includes a heavy duty Taylor 9198 cylinder with embossed graduations and a snap-on cap. Also includes 4 AA batteries and the required pill-shaped magnetic stir bar.