These models are further fitted with THS, an emergency electric seat belt with SRS that consists of multiple airbag modules to support the head/s, chest, and pelvis of both the driver and front seat passenger during a head-on or frontal collision. It has an air bag control unit at the center of steering wheel and another at right side of the instrument panel, two impact signals at both sides of the radiator and the sensing-diagnostic unit at below the panel. Some models also have side airbags and curtain shield airbags for the side impact and further impact sensors are situated near the front and rear seat belt retractors. Airbags are also associated with other pyrotechnic devices; seat belt pre-tensioners which tightens seat belts in an accident. Inside the steering wheel housing there is the air bag inflator insert which comprises a cushion and inflator part and a spiral cable assembly of electrical signals irrespective of the position of the steering wheel. The passenger side airbag is also bigger than the unit mounted on the steering wheel, positioned above the glove compartment and with a trim cover which splits during inflation. Front seat torso side airbags and curtain shield airbags are deployed on the roof line extending from the front A-pillar to the rear of the passenger compartment. Sensing and diagnostic module supplies current to the airbag system at a time of an accident and tests the system each time the vehicle is started an indicating this by blinking the AIR BAG light. In response to a fault, the light remains on and if it continues to flash or give out a beep sound, it has to be serviced. Measures that should not be taken involve operating in the vicinity of the SRS system that is the steering wheel or instrument panel provided the wheels are straight; the ignition key should be turned to the LOCK position; one should not disconnect the negative terminal without first informing everyone; one has to wait for at least two minutes after disconnecting the negative terminal as this is the time the backup power supply uses, among others. To reduce the risk of airbag explosion, one should ensure that, when working with an airbag module, the opening of airbag should not be positioned towards the body plus, the airbag should not be put on any surface with the opening facing down. Any measurement of the resistance of any SAS component is prohibited, and electrical welding should not take place on the car with the airbag without the removal of the negative cable from the battery. A live airbag module cannot be disposed of; it should be taken back to a dealer to be deployed and disposed of correctly.