For reproducible results and liquid transfer. Hei-Flow Expert pump includes premium safety standards and features for superior ease of use and reduced cost of ownership, including:r- Adjust the variable speed from 5.0 - 600rpm on the analog control knob. Your speed is held constant even under changing loadsr- Electronic speed control at an accuracy of ± 0.5%r- It connects to an optional foot-pedal remote control via cable to start and stop your pump drive outside a closed fume hood increasing your personal safety or ease of use in multiple sample fillsr- At the press of a button the pump operates clockwise or counter-clockwiser- A press of the max button accelerates the filling and draining of your tubing rSupplied without pump heads. Please order separately.r-Power supply: 230 V.