Abstract: A passive infrared intrusion detector is configured to resemble an electrical wall outlet. The unit includes a light for visually indicating the direction of its beam of sensitivity, and a lens unit which facilitates directional adjustment of the beam.

Abstract: A passive infrared intrusion detector is provided with a lens having selectable patterns of sensitivity. The lens unit can be mounted to the detector in two orientations to provide two different patterns of sensitivity.

Abstract: An improved arrangement for orientating an apparatus which is adapted to transmit, receive or relay electromagnetic or acoustical energy is described. The apparatus includes a housing and a housing positioning means and a housing mounting means are provided for mounting the housing to a support body. The housing includes a housing member having an elongated surface which is adapted to be positioned adjacent a surface of the support body. The housing surface has a cross-section configuration for providing a first plurality of alternative orientations for the apparatus while the housing positioning means is adapted to be located between, and in contact with, the housing member surface and the support body and to cooperate with the housing member surface to provide a second plurality of alternative apparatus orientations.