This means that the diameter of the screw is12mm, and the pitch is1.25mm. When changing oil, you need to use a wrench of appropriate size to loosen and tighten this screw. Please make sure to use the correct tools and methods to avoid damaging screws or other oil system components. If you are not sure, it is recommended to consult the user manual of Da Yang Xiaofeng 150 or consult a professional for accurate information.