This is called The Addalock.
It is a portable door lock and installs in seconds, no tools required, which I like because the Resident Assistant can be stingy about loaning out the tool box!
You can use this on any door that has hinges and opens inward.
So remember that roommate situation?
This is also a great tool to use in hotel rooms for an extra level of safety.
It never hurts.
It’s also affordable!