Levelers are a group of English political activists in the 17th century who advocated for social and political equality. They were also known as the 'Levellers' and their main goal was to limit the power of the monarchy and create a more democratic society. The term 'SHIMS' is used to describe thin pieces of material used to fill small gaps or spaces between two objects. In this context, the term 'SHIMS' can be used to describe the Levelers' efforts to level the playing field between the monarchy and the people.