Mini DC Voltmeters:Total 10PCS, 5 colors combined(2PCS Red/Yellow/Blue/Green/White) 0.28 inch LED Panel:small in size and light in weight; wire is made of 28awg gauge; install the hole: 23*10 mm approx 2 Connection Methods:3 wires are connected separately to measure voltage and power(Red yellow is both for pos, black is neg); 3 wires are used as 2 wires, connected to measure voltage(Red and Yellow can be paired for pos, black is neg) Features:Reverse polarity protection, voltmeter won't burn out if reverse polarity is applied; high precision; low starting working voltage; fine adjustment function Note:Max voltage with yellow and red connected is 40V.To measure greater than 40V (up to 100V) the yellow wire is connected to a separate voltage source that is 40V or less ASIN B0BG31FBX5 Color Any one of the colors: Red, Yellow, Blue, Green, White Model S0100-10K Brand Name Sumklin Style Name Compact, Modern Unit Count 10.0 Count Item Weight 0.05 Kilograms Part Number S0100-10K Manufacturer Sumklin Power Source Battery Powered Measurement Type Voltmeter Compatible Devices Itself, Electrical Circuits Upper Temperature Rating 65 Degrees Celsius Minimum Operating Voltage 0.1 Volts