MT-33D+ KOOCU High Precision Digital Multimeter, a Diagnostic Tool Used To Measure Electrical Properties Like Voltage, Current, and Resistance. Display: The device features a Large screen display for easy reading of measurements. ​Controls: ​Power on/off: Located on the left, a dedicated button turns the unit on and off. ​MAX/MIN Flashlight / Backlight: Located on the right, this button likely controls these special functions. ​Functional area: The central dial is the main selector for all measurement types. ​Test Ports: ​Transistor sockets: There are two sockets for testing transistors, one labeled "E B C E" at the top and another unlabeled one at the bottom. ​10mA Current positive jack: The far-left jack is for positive connections when measuring current up to 10mA. ​COM jack: The central jack is the common negative input.