The invention recites an apparatus that delivers a fuel additive to a fuel. The method inserts OpenFlow OAM packets into an OpenFlow data flow to monitor the OpenFlow data flow, wherein inserted OpenFlow OAM packets have fate sharing with data packets in the OpenFlow data flow. Dimples are formed on the cover surface to satisfy a total number of 360\u2013492 and a percent dimple volume VR of 0. Differential mode signals, on the contrary, after entering the circuit, can pass through the circuit with minimum loss. The developer casing includes a first fixing member and a second fixing member opposite side of the first fixing member in relation to the accommodating section.