A security apparatus includes a mount and a sensor body with a socket recessed into the sensor body at a first angle from a functionality plane. The mount includes a stem and a base adapted to be affixed to a wall. The stem extends from the base at a second angle from horizontal. The functionality plane is set at an angle from horizontal equal to the first angle plus the second angle if the stem is inserted into the socket with the first side of the stem in close proximity to the first wall of the socket, and the functionality plane of the sensor body is set at an angle from horizontal equal to the first angle minus the second angle if the stem is inserted into the socket with the first side of the stem in close proximity to the second wall of the socket.