The Cardinal Gates 21.75"" Gate Extension (Model Bx-2) is compatible with the Cardinal Gates Auto-Lock Gate (Model MG15), Stairway Special Gate (Model SS30), and Outdoor Gate (Model SS30-od). This aluminum extension adds 21.75"" of width to your gate, allowing it to accommodate larger openings. It includes all necessary hardware for easy attachment and is available in White, Black, and Brown.