Features: Brand new and high quality Mini DC Voltmeters:Total 10PCS, 4 colors optional; 0.28 inch LED Panel; small in size and light in weight. 2 Connection Methods:3 wires are connected separately to measure voltage and power(yellow red is both forpos, black isneg); 3 wires are used as 2 wires, connected to measure voltage(Red and Yellow can be pair forpos, black isneg). Features:Reverse polarity-protection, voltmeter will not burn out if reverse-polarity is applied; high-precision; low starting working voltage; fine adjustment function. Note:Max voltage with yellow and red connected is40V.To measure greater than40V (up to 100V) the yellow wire is connected to a separate voltage source that is40V or less. Good quality: This product is made of high-quality materials, exquisite workmanship, very good quality and long service life. Specifications: Material:ABS Color:Red/Green/Yellow/Blue Working current: < 20mA Display mode: 0.28"LED Size:Approx. 30x11.7x9.2mm/1.18x0.46x0.36inches Installation opening: 23x10mm Measurement rate: 200mS 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. Package includes: 10Pcs DC Voltmeter Display