It's debatable if these things are a good idea, since they basically trick your phone or tablet into thinking it's plugged into a dedicated charger instead of your computer. That can result in your device trying to draw a lot more current than the computer's USB port is designed to supply. A bit like wrapping tin foil round a fuse! There is the possibility that you could damage your computers 5V USB bus by overloading it. You can also make your own simple USB protocol defeater by getting a standard USB lead, cutting the data lines and shorting them together at the end with the charging device to make it think it's plugged into a charger. But again, it's not recommended. If you have a large screen phone and are having issues with battery life then a better option is to carry a proper charger or power bank. An easy way to reduce your devices power consumption for longer run time is usually to turn screen brightness down. That will also extend the operational life of the screen's backlight. I don't actually recommend that you use a device like this. The bottom line is that it can potentially damage your computer/laptop by overloading its USB ports. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and dodgy USB devices at https://www.patreon.com/bigclive
Peter Cook and Dudley Moore - One-legged Tarzan sketch. There are a few versions of this one, but this is surely the best.