The Cheminert Model M6 and M50 liquid-handling pumps produce a bidirectional pulseless flow with a range of over six orders of magnitude (5 nL/min to 5 mL/min for the M6 Pump; 1 µL/min to 25 mL/min for the M50 Pump). A viable replacement for syringe pumps, the M6 and M50 offer eliminate the need for refill cycles and syringe changes. They are self-priming and tolerant of any gas which may find its way into the fluid lines. There is no separate fill cycle, and the capacity is unlimited. Other features include RS-232 and RS-485 communication protocols and a software package that controls flow rates, flow direction, and metered volumes. While the standard package includes software and instructions to run the M6 as a stand-alone unit, the software can also integrate a multi-position stream selection valve.