Features: Use: It works for DC 4-100V, mini size and easy to install, work great for checking voltage. Large display: 3-digit LED digital tube, large numbers, quickly and easily read. Opening hole: The opening hole diameter is 30cm, easy to install. It is made from good quality plastic, which is durable, long lasting. Reverse connect protection: It can be protective when connect the wire inversely or wrong. Compact design: It is compact, mini size and portable, easy to store and carry. Package Includes: 1x Volt Detector Specifications: Material:Plastic Size:Approx.3.38x3.38x1.8cm/1.33x1.33x0.7inch Color:Red/Green/Black Measuring range 5V-100V Power supply range 5V-100V Minimum startup 3.8V Allowable error 1% Input impedance100K ohm Working current red 15mA, green 12mA, blue 12mA The refresh rate is about 300mS/time Display mode bit round LED digital tube Display color red, green, blue optional Lead length 20cm Overall dimension diameter 33.8 Hole size diameter 30.0 Display: 3-digit round LED digital tube Working temperature: 10~65 Warm tips: The input voltage can not exceed 100V or the voltmeter will be damaged. note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks for your understandings.