The John Drummond test lamp and proving unit includes an MTL15 test lamp coupled with a PD690S proving unit and the TC69 combination carry case. Safe electrical work requires the use of a voltage indicator or test lamp that has been proved with a proving device before and after use. This TC69 soft carry case ensures that your proving device is always on hand and provides the simplest solution for implementing safe isolation practices for electrical test equipment. For convenience and to save time, the proving unit can be used without having to remove it from the case. The PD690S voltage and power output are matched to the MTL15 to illuminate all voltage bands and prove the test lamp is functioning correctly. The 1.5V alkaline batteries are required for the power supply to the proving unit.