The Schrader TPMS Solutions TPMS Retrofit Kit, No. SCHRFK4S, is designed for vehicles built before 2008 without a factory-installed TPMS. With a dash-mounted receiver/display and four wheel-mounted transmitters, the kit enables real-time pressure and temperature monitoring of all four tires as well as a spare if a fifth sensor is bought separately. The solar-powered wireless display keeps users informed of each tire's status and warns users of under-inflation of 25 percent or more.