I had forgotten about these! They went through a phase a long long time ago, when computer peripherals such as CRT monitors, printers, etc could be real power suckers, and you often had lots of peripherals with their own power supplies such as modems, external floppy drives and scanners and such that they made some power strips with a master outlet that when it sensed the power was turned on on the "main" device, the others would power up. They were generally very unreliable, both in functioning correctly in toggling power as well as lifespan for the premium price. Old school analog circuits in them, I'm sure.
It's cool they've made a comeback