These Overhead Stirrers feature high torque and advanced digital microprocessor control for smooth mixing of low and medium viscosity samples. Speed and run time are accurately set and monitored on the LCD screen. Both the 20L and 40L capacity models are supplied with a 4 arm stainless steel propeller, additional steel and Teflon accessories are available. A feed-through chuck holds accessory shafts firmly in place and is easily tightened and loosened without tools. The overhead stirrers are protected from damage by sensors that shut down operation in the case of high viscosity or obstruction, while a splash cover protects the connection mechanism from potential corrosion. Unlike most mixers, the Benchmark series is also supplied with a support stand and mounting hardware. The stirrer easily and securely attaches to the stand for compatibility with a variety of vessels, up to 24 inches high.