In most hotels, the most secure method to prevent unauthorized entry and allow only the guest to enter a room is by using a key-card pre-programmed by the hotel management. For this, it makes sense to use readily available magnetic key-cards and readers with encrypted, hotel-programmable codes. Before the card reader can read the magnetic strip on the key-card, it needs to receive an indication that the card has been inserted fully. This is achieved with a small spring loaded lever having a tiny magnet which is pushed by the key-card when it is inserted fully into the slot. When the key-card is inserted and the magnet is pushed towards the sensor, the signal from the sensor is can be used to trigger the magnetic card reader which then accepts or rejects the card. When accepted, the controller can then trigger a solenoid or a motor that opens the lock. Hermetically sealed Reed Sensors are especially useful in areas like locks where there needs to be grease, lubrication and dust.