It is a new product, which is designed to be directly mounted on a small bottle and which is also free to adjust the flow rate. This product, together with the small oxygen bottle and the nasal breathing pipe constitutes a set of medical oxygen supply instruments which is an ideal type of portable breathing apparatus for using as first aid to those who feel short of oxygen or gasping in an emergency. This product is indispensable for a medical unit or such places as theatres or a meeting halls to keep as medical apparatus and is also fitting to be carried with in a long distance passenger transport or in a polluted environment or on a special operation. It is also suitable for doing mini-welding and mini-cutting repair jobs as well as for making experiments in laboratories.