For mounting large or heavy materials to a surface, each of these concealed connectors consists of two fittings that interlock to form a strong, rigid coupling. One of the fittings attaches to the mounting surface and the other to the item being secured. A locking tab ensures permanent, tamper-proof installation, but can be removed prior to assembly to allow use as a knock-down connector, letting you detach the parts whenever needed with a lift-and-pull motion.