Bird nesting material box;Contains natural cotton thread fibers which are great for nest-building;This box contains the extra nesting material you need to make your bird's nest comfortable and cozy;The box easily attaches to any cage and the perforated hole pops out with a simple push so birds can have quick and easy access to the fibers;Box measures 8-1/4-inch length by 7-7/8-inch width by 5-1/8-inch height