Features: 1. The same port can output reference voltage: 2.5V, 7.5V, 5V, 10V. 4mm banana socket output interface. 2. Compact and portable: being so mini and light-weight, this product does not take much space and can be easily taken away. 3. Durable material: This product is made of high quality plastic+electronic components material, durable and long service life. 4.Built-in AD584, highest accuracy and stability. The MCU switch 4-way reference output voltage with LED indicators. Specifications: Material: plastic+electronic components Color: transparent Power supply: 3.7v Li-polymer battery (not included) Package Included: 1*Voltage Reference Module(batteries not included) Note: 1. Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the pictures. 2. Please allow slight dimension difference due to different manual measurement.