EFO Manufacturers a range of battery powered true AC waveform output proving units. Our proving units provide a safe and reliable means of checking the correct functioning of Multi meters and two pole voltage indicators. before and after use as advised in the safe working practice for electricians. The test voltage generated is at 50Hz to synthesise a genuine test at AC mains supply frequency. Additionally they have the capability of checking the Operation of Non-Contact voltage detectors. Furthermore we select with best quality and value products. Consequently Saving you time on confusing options.