This goes in between the screws and the plate of a lever light switch to block it from being flipped. It is useful if you have smart lights, security lights, or a boiler plate. It is a remix of Yllonnoce's light switch lock on Thingiverse (https://www.thingiverse.com/thing:69806), and it omits the cross circle found on the top of the original model for a sleeker look.
The author remixed this model.