The device was allegedly made for law enforcement, to help them assess hazards before opening a door. You can use the peephole to creep out your friends if you want to purchase it for $88.
Implications - The peephole reverser is all black, simple to use and is small enough to easily fit inside your pocket. The sneaky tool will be handy for police officers but poses privacy threats for others who may want to get their hands on one. Almost all hotel rooms have peepholes, so any one with one of these devices could be spying on you! Scary!