A waveguide type duplex filter having first and second waveguides which each comprise filtering means tuned to a given frequency, comprises two halves having a conducting surface. In some embodiments, shared data may be retrieved from a message passing interface program, wherein the shared data is sharable by a plurality of processes. The stopper body may be detachably coupled to the stopper head andor the strainer to enable selective removal of the stopper head and the strainer from the stopper body when the stopper body is installed for use and coupled to the control element. Thus, the ink jet recording apparatus can store a predetermined amount of liquid stably in the sub tank. The pivot movement of the hook from concealed position to deployed position is urged by a second magnet, which second magnet holds the hook in the deployed position, thereby facilitating the setting of the hook in the fish’s mouth.