Danny, their /4 changes the base sensor count before calibration and depending on the length of your probes, there should be no need to install this device between the probe and FLC.
I have 2 4' Vision Micro Systems probes in my wings and they interface seamlessly with my EI MVP-50. Their /4 device is
required in line when the probe is short as in my header tank...16".

Angier Ames
N4ZQ