An optical member of lighting device is revealed. The retention member is moveable between a first, open position, wherein the conduits can be \u201claid in\u201d to the support bracket, and a second, closed position wherein the retention member retains the conduits in position within the support bracket. The invention also relates to compositions comprising the nucleic acids, polypeptides, antibodies, variants, derivatives, agonists and antagonists of the invention and methods for the use of these compositions. The data is continuously compared to a predetermined wind friction threshold. For each corresponding feature identified in each set of 2D images, an orthographic projection model is applied, such that rays are projected through each point in the feature.