Birdie Bell w/nesting Material. An all-weather holder filled with nesting material. Refills available. Versatile enough for holding seed bells and fruit. The only nesting material available that contains a mixture of five natural-colored materials preferred by North American Nesting Birds! Feathers, String, Cotton, Hemp, and Aspen fiber all included! Because it contains all of the above, this nesting material attracts many more birds than cotton only mixtures.