A method for detecting decrease in tire air-pressure in which decrease in internal pressure of a tire is detected on the basis of rotational information obtained from tires attached to a vehicle. The wafer level packaging includes a transparent enclosure portion adapted to permit image acquisition of an image by the image sensing device over a desired range of wavelengths, and a first spacing structure providing a cavity between an inner surface of the transparent enclosure portion and the image sensing device. The light emitting layer includes a quantum well structure made by alternately laminating n well layers and barrier layers and emits light with a peak wavelength of 650 nm to 1000 nm. The bag is disposed inside the body, and communicates with the external environment so as to expand inside the body. There may be no direct mechanical attachment between the first electrical connector and the first guide module. The pivot point is moved from the first side of the centerline to the second side of the centerline when the lip is contacted by a vehicle that creates a downward moment on the lip.