The Harvard PHD 22/2000 Advance Syringe Pump family is the most versatile of the pump lines. This pump is available for infusion only or infuse/withdraw models. This is the only pump that is available in a Push/Pull configuration. All pumps have RS-232 communications capabilities, but there are also PHD 22/2000 pumps that are programmable directly from the keypad. In addition, a multitude of syringe racks are available to hold 2, 4 or up to 10 syringes. A microliter syringe rack is also available for microliter applications. Remote versions are also available where the control box and pumping mechanism are separated by a 9.1 meter (30 foot) cable.