A housing assembly includes a housing, a camera bezel and a retaining structure. The method and apparatus of the present invention does not require the use of a semi-permeable membrane or other specially formulated material, nor does it require heating or cooling of the fresh water or salt water solution. These 2-substituted compounds, especially the 2-methyl and the 2-methyl-20S derivatives, are characterized by relatively high intestinal calcium transport activity and relatively high bone calcium mobilization activity resulting in novel therapeutic agents for the treatment of diseases where bone formation is desired, particularly low bone turnover osteoporosis.