mean that part of the electromagnetic spectrum approximately between 10 kilohertz khz to 100 000 khz the integrated circuit 32 and the antenna 34 and or other electronic components are held relative to each other together by a potting material 35 the potting material proofs the ic and antenna from the physical environment and reduces the relative movement of the components to each other and the housing thus reducing vibration and environmental induced damage to the tpms unit the potting material also helps insulate the system electrically and aids in heat dissipation the tpms unit 30 is contained within a housing 40 the housing 40 comprising preferably at least an innermost layer 42 and an outermost layer 44 in another embodiment the housing 40 may be comprised of at least the outermost layer 44 the inner layer for example may be a high temperature withstanding plastic material such as glass filled polyamide u2014 pa66 and the outer layer may be a high temperature and wear withstanding and flexible material such as rubber based materials further layers may also be present such as a shielding layer to reduce or prevent electromagnetic interference either by or to the ic except for that area of the antenna or.