An ingenious screwdriver tester that can be used to detect continuity & therefore for checking fuses or lamps. Continuity tests can be made by holding the tip of the screwdriver on a fuse then touching the cap of the screwdriver & the cap of the fuse with your h&. If the fuse is OK the screwdriver will light. The same principle can be used with lamps leads & anything else that is conductive. Other uses include short circuit tests tracking broken cables microwave oven radiation testing & television emission tests. The device uses two silver or alkaline batteries supplied with a battery life of Approx. 5 hours continuous product use. Dimensions 136 x 20mm L x W including clip.NB Not suitable for direct connection with live circuitry.