Specifications: Type: Coil Tester Material:ABS Color: Red Features: It can be used to check lock loop. Auto lock inspection loop auto car key lock chip antenna tester. If have light on but can't start car, means the chip have problem. Auto lock inspection loop is indispensable for locksmith or key programmer. Checking auto lock loop, if light on means the lock no problem; if no light on means the lock loop have problem. Coil Tester supports all models with chip-reading coils: For Mercedes-Benz 1998-2014 models; For BMW 1995-2014 models; For Audi/Volkswagen new smart test. Usage method: Place the sensor coil close to the ignition switch The key passes through the sensor coil,inserts the ignition lock,and turns the key.