Heidolph Hei-FLOW Value 06 peristaltic pump includes leading safety standards and features for superior ease of use and reduced cost of ownership. Constant speed (50-600 rpm) is maintained under changing loads and set via an analog speed control accurate to plus/minus 2%. Clockwise and counter-clockwise operation at the touch of a button. Single channel operation only with flow rates of 3.0 to 4.151 ml/min. Sold without a pump head or tubing.