Under a special provision of the U.S. Copyright Law and with the permission of authors and publishers of works not covered by that provision, NLS selects books and magazines for full-length publication in braille, ebraille, and digital audio format. Reading materials are circulated through a network of libraries throughout the United States and its territories and to American citizens living abroad. The materials and free playback equipment needed to read audiobooks (called talking books) and magazines are circulated to patrons by libraries by postage-free mail. Digital audio and ebraille materials are also available through the NLS Braille and Audio Reading Download (BARD) online service and the BARD Mobile app for iOS and Android devices.