ITEM NAME:ST201 Digital Black Multimeter Clamp Ammeter Transistor Power Tester M3X4 Description&Preview.1 User Manual. You can follow below process to chontact us. Data hold function, low battery indication, auto power off. Frequencyï ¼Å¡ 10Hz~400kHz 400kHz~4MHz. Import Duties. AC currentï ¼Å¡ 40A/400A. Resistanceï ¼Å¡ 400/4k/40k/400k/4M/ 40M omh.