A circuit including a signal input to receive a signal, a buffer circuit to receive the input signal and to generate a buffer circuit output, and a voltage following circuit to receive the signal input and to generate a voltage following output. A plurality of service request messages are received by a network entity, the request messages corresponding to a plurality of services requested by the user. The retaining clip 11 includes a first wall part 12 fixed at a position different from the terminal of the cover material 24a, a second wall part 14 facing to the first wall part 12, and a connecting part 13 for connecting the two wall parts 12 and 14 to each other.