General Aire 12738 Thumb Screw Assembly
The 12738 thumb screw is used to secure the door to the air cleaner. The part is called a thumb screw because it is meant to be turned with your fingers, and does not require any tools. The screws should work properly for a long time, but eventually, the treading may wear out, and the screw will need to be replaced.
Also known as part 4008. Replaces 12748.