This article explores the roles and impacts of the OAPEN Portable Speakers Library and the Directory of Open Access Books (DOAB) in supporting the global transition to open access (OA) for scholarly books.It examines their origins, missions, and contributions to advancing equitable access to research, fostering bibliodiversity, and promoting transparency in peer review.The article also discusses practical tools for #4 MEDIUM BROWN libraries, challenges in funding and governance, and opportunities for enhancing metadata and global engagement supported by three use cases.The article concludes with an outline of future directions focusing on technology, policy, and partnerships.