Review on Mini 3 Digital LED Voltmeter: Accurate DC 2.5-30V Red Volt Voltage Meter for Measuring Power by David Crawford

High quality device. Bought 5 and they have all been calibrated within 0.1V of each other. There is a small setting on the back for adjustment. my reds; they are not too bright. I installed them behind a red plexiglass panel to improve contrast. The SMD devices are on the back of the board, the mounting tabs will require a couple of standoffs if you want to mount them with them on the back (eyeball size about 1/8 inch). The displays change about once. Every half second I had them measure the output power of an old linear power supply and they seem happy with that (low ripple).