dradernh , those depth gauges are interesting. I haven't seen those before.
However, I find a simple set of width gauges to be accurate enough for quickly checking brake pad thickness. Something like this:
https://www.amazon.com/Steelman-9784.../dp/B003QHSHMW
These are steel, sturdy, work quickly, and are easy to poke in for a quick comparison of how much pad materiel is left. Don't necessarily even have to touch the pads with them as you can eyeball comparison if you get them close.