The optical system of the present invention includes a plurality of lens groups and a variable focus lens. Related service entities managed by different service applications may be matched and consolidated. The preferential distribution of mastic may comprise the formation of a non-planar layer of mastic on the tape. In a second, open position, the top cap anterior internal annular ridge and the top cap posterior internal annular ridge engage the median annular groove and a posterior annular groove of the pen housing, respectively.