The automotive rubber bellows are tubular elastic sensing components joined by foldable crepe sheets in the direction of folding and contracting. Its open end is fixed, the sealed end is free, and the auxiliary coil spring or reed is used to increase the elasticity. The active end drives the pointer to directly indicate the pressure. Bellows are often combined with displacement sensors to form a pressure sensor that outputs electricity, sometimes as isolation components. Since the automotive bellows stretch requires a large volume change, its response speed is lower than that of the Bourdon tube. During operation, it is elongated along the length of the tube under the action of internal pressure, so that the movable end generates a displacement that is related to the pressure. The automotive rubber bellows are suitable for measuring low pressure.