This is what I used for my AFR and voltmeter. AFR is the bottom instrument. It records up to 2 hours of data and you can download it to your laptop with the mini USB port in the front on the lower left and then chart it or make an Excel spread sheet. I records AFR, RPM, and manifold vacuum/pressure. Our host sell this kit.
The "CL" reading on the gauge is for "cold" meaning the wideband sensor is not warmed up yet.
Above digital readout is battery voltage, oil cooler temp, free air temp, and a digital clock. The toggle switches let you toggle through the settings and set the clock.
I cannot over emphasize how critical it is to record AFR, RPM, and MAP data and be able to analyze it later. to me, real time gauges with no data memory is a waste.......unless you have a co-pilot with a clipboard who can take notes really really fast!!!!
I have had this setup in my MFI 2.7 1973 for many years and it has been invaluable in setting the AFR.