A fastener includes a mounting base and an insert portion. The mounting base includes an accommodating cavity having an accommodating cavity opening and a mounting slot located above the accommodating cavity having a width that is smaller than a width of the accommodating cavity. The insert portion includes a retaining portion, a neck portion connected to the retaining portion, and a head portion disposed between the retaining portion and the head portion. The head portion is configured to be received within the accommodating cavity by the accommodating cavity opening. The neck portion is configured such that at least a portion of the neck portion is received by the mounting slot when the head portion is received by the accommodating cavity.