Review on MCIGICM Digital Voltage Tester, Mini DC Voltmeter 2.5V-30V with 0.28 inch LED Display (Pack of 5) by Justin Hines

I asked "What current do they draw for each color?" In my final project I will be running from (2) 9v batteries in series, so 18v. I wanted to know which voltmeter draws the least current so my batteries will last the longest. The winner was (surprisingly!) White. Here are the numbers: Yellow 17.33mA @ 18V Red 14.09mA @ 18V Green 12.51mA @ 18V Blue 9.43mA @ 18V White 6.90mA @ 18V I thought that the white color with multiple (RGB) LEDs is obtained, because I thought that this draws more actual, but this is clearly not the case. I had limited samples of just one order of (5) colors to measure so "your mileage may vary". And I'd love to hear from someone doing measurements like this to see if you think a white display is the most effective. I found it a bit difficult to work with different designs due to the tiny size of the mounting screw and the need for a rectangular hole to see the screen. display over. I tried the nibbler tool and the dremel moto tool but my rectangles never came out right. So maybe manufacturers are rolling out the same small and productive display in a round body? Or maybe someone has a great way to cut the right size rectangular holes in a tin box?