These swab boxes are made of 18pt, virgin fiber, solid bleached sulfate. This stock helps prevent cross contamination and is the sturdiest swab box available. Boxes are pre-cut with 2 breathing holes. Contains no biodegradable components to jeopardize the evidence. The breathable boxes are ideal for cotton tipped swabs. Compact size saves room in kits, on shelves and in labs, Simply squeeze the box and the box pops up to prevent contamination.