Review on 🔌 iUniker Power Switch for Raspberry Pi 3, Pi 2, B+, Zero W - 4-Pack, Raspberry Pi Power Supply Cord with On/Off Push Switch, MicroUSB Female to Male Cable by Randy Robinson

So far the three I've used have worked. You press a button, electricity flows. Press the button again and the power will stop. While it works well, it's VERY hard to tell if the power is on or off. This switch really needs either a bigger button or some other physical way to indicate the on/off position. A small LED display would be very helpful. I've attached some pictures to show the difference between on (top) and off (bottom). In my experience, these positions are also counterintuitive. Upon receipt and prior to use, inspect the switches to ensure they are in the desired operating position.