Testo 750 series voltage testers testo 0590 7501 the testo 750 1 voltage tester has an all round led display that can be seen from any position and guarantees an ideal voltage indication thanks to its unique fibre opticsit meets the latest voltage tester standard en 61243 32010 and meet cat iii 1000v cat iv 600v safety standards testo 0590 7501 750 1 voltage tester