A vacuum cleaner includes several attachments and an attachment unit for accommodating the attachments. By transmitting a second frame that repeats the truncation of the TXOP transmitted from the first station, a hidden node problem can be avoided and equitable access to the medium provided by ensuring that stations that may be outside the broadcast range of the first station also receive the frame truncating the TXOP. The first layer and the third layer are arranged so that a second layer is sandwiched between the layers in a state in which the surfaces provided with the grooves face each other. The through bores start from the connection face and end in one of the first attachment faces. The threaded cylinder includes a threaded portion corresponding to the spiral shell pillar.