A flow meter includes a flow path through which a fluid flows; a pair of transceivers for sending and receiving an ultrasonic wave propagating across the flow path; and a flow calculation section for calculating a flow rate of the fluid flowing through the flow path based on a result of the ultrasonic wave being sent and received by the pair of transceivers. The cap surrounds a portion of the electrical assembly of electrical components to form a pocket between a portion of the electrical assembly of electrical components and the cap. The aperture has a base towards which the interior bottom surface extends. This enables the mirror to appear as if framed by an integral frame assembly without suffering the drawbacks of making, handling and using such. The invention allows for flexibility in the addition and removal of nodes or groups of nodes to and from a network without interruption of the queuing capabilities of the network. The coil arrangement includes first and second terminals having a geometry different from one another and from the active coil winding of the arrangement.