These fast and accurate electrodes do not require an external referencethey're easier to use than separate sensing and reference half-cell electrodes. As double-junction combination ion-selective electrodes, they are convenient to use in places where two electrodes won't fit. All electrodes include a 30-mL bottle of reference solution, a reference filling pipette, 1-m cable, BNC connector, and an instruction manual. Use electrodes with a meter that has a resolution of 0.1 mV for the most accurate results.