Martindale Proving Unit is designed to enable voltage indicators to be fully checked, in compliance with health and safety recommendations. Using a voltage indicator without first proving it is working correctly could prove fatal. Compatible with the new Martindale VI13800 and the Martindale VI13700. It can also be used to check Drummond and other filament test lamps as well as standard multimeters and other manufacturers two pole voltage indicators. There is now a facility to power the proving device with the addition of a 12VDC power connection point. The unit can be powered by either alkaline batteries or a 12V power supply. There are two power supply units available for the proving devices, the PSUPD230 and the PSUHPAT12. The PSUPD230 can be connected to mains power and the PSUHPAT12 is a 12v power supply suitable for use in a car/van cigarette lighter.