ITEM NAME:DC-DC 4.5-40V to 5V 2A Step-down LED Voltmeter USB Buck Voltage Converter M P3C4 DC-DC 4.5-40V to 5V 2A Step-down LED Voltmeter USB Buck Voltage Converter M P3C4 The voltmeter has automatic calibration function. With reverse connection protection. With overheat protection and short circuit protection. With USB power indicator light. High efficiency and low ripple. Name:Step down voltmeter module Input voltage:DC 4.5 ~ 40V. Output voltage:5V (when the input voltage is between 6.5V ~ 40V). Output current:2A. Application: can be used on car, electric bike, motorcycle for voltage measurement and to charge phone, iPad, Mp3 etc. Size:approx 5.7cm x 2cm x 1cm(LxWxH) Color:blue Material:CCL Instructions: When you need to charge the mobile phone, Ipad, MP3 and other digital products, touch the "output enable" button, then the USB power indicator light on, the USB output voltage 5V ; When you need to turn off the digital tube, touch the "low power" button, then the module into the ultra-low power standby mode, USB output is also turned off accordingly. Package Included: 1 x Step down voltmeter module Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm..With overheat protection and short circuit protection. Output current:2A.