First is single stage systems, single stage heat pumps, single stage air handlers. And with those types of systems, when the system turns on, there's a just an either on or off. It's almost like a light switch. There's no in between and that light is either on or it's off.

Next category is staged systems. so two stage, three stage I've. seen some systems have even more stages than that, but essentially it's a staged system and the idea would be instead of that on or off, like the single stage, there's going to be some inbetweenies there. Maybe instead of running at 100% capacity and zero, Maybe there's a 70% Maybe it's a two-stage system that goes to First Stage being 70% and then second stage being 100% So that's the second category.

And then the third category is inverter systems and.