This is a cute decoration that fits over switch plate covers. There are different sizes and styles of switch plates. In my home there are three or four different sizes for a single range light switch. These models fit the ones I seem to have the most of. 

The bottom piece is designed with a hanger that matches the screw hole for a modern and another that fits most classic light switch styles. The top piece just has a tab that fits between the switch plate and wall to hold it in place.