A color analyzer is a type of darkroom meter that also measures color balance in addition to enlarging times. This is a simple unit: you make a print from a negative you like. You place the sensor box under a spot on the negative and null out the meter--skin tone is a common one. Then you put in the next negative, put sensor on a spot that has skin tone (or something you want to come out the same shade of gray), and change the aperture until the meter nulls out.

You do something similar with the color, except that you use a diffiuser to blend all the colors together. You start with standard negative (or transparency) and make a print you like. Then you put the diffiuser under the lens, put the sensor under it, and for each color channel (cyan, magenta and yellow) you null out the meter. For your next negative you place the diffuser under the lens, put the sensor under that, and the meter tells you which filters you need to print it.

This one is a nice because it's fairly small and it has a bracket to mount it on the wall, and it's simple enough that you can figure it out without an instruction manual (which mine doesn't have). It also has a little tab to protect the sensor from bright light, something sorely lacking in my Labosix. The only thing I don't like about it is that it has a big sensor cell, which is fine if you're using the diffuser to read the color cast, but not good at all if you're trying to read small spots on the negative for exposure (i.e. zone system work).