Big Edit: Solved! Thanks to everyone who helped me with critical information about this very little thing that doesn't affect any of you in a direct way. I am very grateful.

Original post-------------------

Question for #electronics people, #engineer people, etc.: What are these used for?
These are labeled (FB marketplace pic) as Woods XFC-2001 0B micro-inverters. What kinds of applications do they have?

Edit: The internet search engines are eager to tell me what the brand and model of these are (which I already know), but I'm coming up short trying to find what they're used for.

Edit 2: Welp, since somebody has 4 of them for sale, $10 each, half an hour from my house, I guess I'll own four of them if all goes well :)

Edit 3: Guess who's got two thumbs (currently) and four micro-inverter VFDs! This guy!

#question #whatfor

@guyjantic Made to drive 3-phase motors by producing those three phases at different frequencies.
I use them to drive larger stationary tools that can use variable speed: band saw, power hammer, sander/grinder.
@Flux Oh, excellent! And now I have four of them, so I'd best buy two more motors.