The 4910 and 4911 are Electronic DC Voltage Reference Standards which feature four separate and highly stable 10V outputs. While their performance is comparable to that of saturated Weston standard cells, they eliminate most of the drawbacks encountered in standard cell use and maintenance. In addition to replacing saturated Weston cells as a laboratory standard, the 4910 and 4911 can also be used as a readily transportable standard. The 4910 and 4911 DC Voltage Standards are based on the latest zener-diode technology. Their four separate 10V outputs are fully independent, but can if required be averaged to provide a very low noise 10V output on separate front-panel terminals. The provision of both individual and average outputs enables direct inter-comparison between the cells at the output terminals, allowing excessive drift in any cell to be detected without the use of higher accuracy standards. The individual outputs-are adjustable to within microvolts of one another, so that inter­ comparison is possible to a very high level of accuracy. In addition to itsfour individual cell outputs and its average 10V output, the4910also features IV and 1.018V outputs, and a low-impedance 10V output with 4-wire sensing. In their normal operating mode, the units can be powered from an ac line supply or from their internal batteries. Both models also feature a special low-power transit mode, which can be used during transportation or shipment of a unit to maintain its calibration. In transit mode, power can be derived from the unit’s internal batteries, from an external DC supply, or from an AC line supply.