Power Supply: external connection micro USB-5V or external power DC 15-30V, each way makes the generator work, both ways also can be connected at the same time. Battery is not included. Voltage Output: DC ±10V, precision is 0.01V, rotate the encoder knob to adjust output voltage, can be calibrated. Current Output: 0-22mA, precision is 0.01mA, rotate the encoder knob to adjust output current, can be calibrated. Multiple display: just push the small botton to switch the display mode between voltage and current, you can also follow the instructions to switch 0-100 percent or 0-50HZ display. Product Dimension: 3.94” x 2.36” x 0.79” (100mm x 60mm x 20mm), portable and convenient. Battery model: DC 3.7V 1000mAh 803040 UCTRONICS signal generator is designed to simulate 0-10V voltage signal and 0/4-20mA current signal for PLC and panel Debugging, Device Testing, Frequency Converter, Flow Valve, ect. Very easy to use, it can be connected with micro USB-5V power supply or DC 15-30V external power. What’s more, it can display 4 different types of digit,-10V-10V voltage, 0-22mA current, 0-100 percent and 0-50HZ. It will play a important role in your electronics work. This item does not include any battery inside.