In a perpendicular magnetic recording system, the data that is being written by the write channel is fed back into the read channel. The shell includes a roof, a floor and a wall between the roof and the floor. Each element in the structure is linked to at least one other element in the structure. Accordingly, line breakage due to electromigration is substantially prevented, thus improving electrical characteristics of the device. To provide an optimal consumption of sealing fluid, a valve mechanism is arranged to the mechanism for providing the cooling sealing fluid flow, the valve mechanism being arranged to react to the temperature of the seal and to open and close the flow of sealing fluid according to the cooling need.