The Steel Door Institute (SDI) was established in 1954 as a voluntary, non-profit business association that develops quality and performance standards for steel doors and frames. Representatives of SDI member companies create and publish these standards, which are made available without charge to architects and other design professionals to ensure quality and consistency of hollow metal doors and frames used in construction. As a complete hollow metal door and frame resource, the SDI website provides all standards, an extensive set of Frequently Asked Questions, and a Gallery of Products. SDI also offers online education for AIA and GBCI credit. SDI members are steel door and frame manufacturers who have passed an on-site audit from hollow metal door and frame engineers. When you specify an SDI door you can be assured you will receive a product that is well-constructed, tested, and evaluated to meet your specifications.