How Does Universal Active Styluses Work?

Question

I have a simple capacitive touch screen 2-in-1 and I have explored different stylus styles in the past. I stumbled back into them and found information on Bluetooth active styluses; however, when I search for them on say Amazon, I get active styluses that are universal and not-Bluetooth enabled. How the duce do those work? If they require power, then what is the power used for and how does it communicate with most capacitive touch screens? The link is to an example of one on Amazon: stylus on Amazon

Answer 1

The active styluses create an electromagnetic field which mimics the change in capacitance similar to the hand. I still wonder what the circuitry looks like though.