Guaranteed proof against loss, mislaying, theft or counterfeiting: Using a finger as a front door key. Siedle Fingerprint provides the convenience and security of biometric identification to every front door. Siedle uses the most secure technology available: A thermal line sensor with alive recognition. As the finger is not placed on but drawn over the sensor, it does not leave any usable traces. At the same time, the sensor is continuously cleaned through use. Siedle Fingerprint can be used without restrictions in outdoor environments.