I wonder if an inductive current or magnetic field could be used to toggle them 'on' and 'off'?

Ok, I used the wrong term to describe what it was they were defending. I'll give you that. But according to the trademark claim, "Color is not claimed as a feature of the mark." Fluke states on their own trademark claim submission that they are not defining a specific color as part of their trademark. Doesn't that remove their claim of "The yellow makes it look like ours"? And when a color is part of a trademark claim, it has to be a VERY specific definition of that color, doesn't it?

Used to be that you trademarked your logo and your model-name. But trademarking your colors, shapes, etc. is ridiculous. How is this different from Toyota AND Honda selling yellow cars? If it looks like a Fluke, and I pick it up and see SparkFun on it, I think, "Heh, they copied Fluke's design". It's not disingenuous. They're selling an inferior product for a much smaller price to people who don't need a $3000 Fluke meter to check their robot's power relay. They're not labeling it or branding it as a Fluke. How does this harm Fluke's IP?

Doesn't have to be unbreakable indefinitely. Only has to be unbreakable until the VC checks clear.