The SHIMs (Shove Hardware in the Middle) are a new range of boards designed to be small, affordable and handy. They're just 0.8mm thick (the bare board, not including mounted components) and designed to be soldered straight onto the GPIO pins of your Pi, if you wish, so that you can use them with HATs and pHATs on top.
Just plug your micro-USB power supply into the micro-B connector on OnOff SHIM, and then press the button once to switch on power and boot up your Pi. After installing the software, you can press and hold the button for one second to initiate a clean shutdown and completely cut the power to your Pi.
Note: This product requires some soldering