This thesis describes a device for preventing loss or theft of an item, using distance and motion detection. The concept from the user point of view is a device that allows to be moved by the owner only. The connection between the device and the owner is established by an app on the owner’s phone. The device is aware of its distance from the owner (i.e. from the owner’s phone). When in proximity, the motion detection algorithm is disabled. When the user is far away or absent, the motion detection algorithm ensures the security of the item. The minimum configuration of the device comprises: a BLE transmitter configured to transmit a short range signal, a motion processing unit to compute 3-axisaccelerations and angular velocities, a central processing unit, a buzzer to alert the user.