The MSL Digital: https://www.msldigital.com/pages/more-information
has its own micro USB port
While the Mausberry Circuits: https://mausberry-circuits.myshopify.co ... own-switch
connects to the RPi's existing micro USB port
I believe both are plug and play, as in no script is needed if you just want to shut your RPi down safely and also turn it on.
EDIT: you know what, I think you do have to install a script for both to work. bummer.