optical elements 28 30 32 34 36 38 relative to the housing 12 without departing from the scope of the present disclosure still furthermore while the clips 66 68 shown in fig3 are associated with the housing 12 those skilled in the art will appreciate that the clips 66 68 may be mounted on the optical elements 28 30 32 34 36 38 for engaging the housing 12 particularly a rib flange notch or like feature on the housing 12 in one particular aspect the front and rear clips 66 68 may be integral with the housing 12 for example the front and rear clips 66 68 may be formed by roll forming or break forming during construction of the housing 12 in another aspect the front and rear clips 66 68 may be separate components that have been connected to the housing 12 for example the front and rear clips 66 68 may be mechanical clips that have been secured to the housing 12 with fasteners e g screws or rivets accordingly the front and rear clips 66 68 positioned within the housing 12 may facilitate precise alignment of the optical elements 28 30 32 34 36 38 relative to the receivers 16 18 20 22 24 26 in an off axis configuration thereby simplifying the installation process furthermore when the window 14 is.