Suitable For Use In Environments With Temperatures From -10 To +65c And Humidity From To . Adjustable Voltage Resistor: By Rotating The Voltage Resistor Clockwise, The User Can Easily Adjust The Device For Use With Various Power Sources Includes 5v, 9v, 12v And 24v. This Allows For A Variety Of Applications In Different Electronic Setups. Protection Design: Equipped With Reverse Polarity Protection To Prevent Damage Caused By Incorrect Battery Installation Although The Meter Will Not Burn Out, It Will Not Display A Reading Until The Polarity Is Corrected, Thus Increasing The Durability And Usability Of The Device. Measuring Range:red Dc4.50-30.0v, Green Dc4.70-30.0v, Blue Dc5.00-30.0v Power Supply Range:no Need For Additional Power Supply, Directly Use The Measured Voltage As The Power Supply, The Range Is The Same As Above Maximum Input:dc30.0v. Note: Input Voltage Higher Than 30v May Cause Permanent Damage! Allowable Error:; When Greater Than Or Equal To 10v, The Error Is 0.3v; W