This 3 piece thin metal die set is part of the Hero Arts Looking Glass Dies. These dies are compatible with leading die cutting machines (sold separately). These dies are designed to layer in a variety of ways to build 2.25" squares. This set of dies is perfect for slimline cards and can be used with other stamps from Hero Arts (sold separately) to make gorgeous cards, scrapbook pages, and more. These dies are designed for cutting windows, creating backgrounds, and building layered scenes.