The Sony ALC-F55G 55mm Front Lens Cap is a replacement cap for Sony Alpha series lenses that feature 55mm filter threads. Keeping the lens covered when not in use will protect it from dust and/or scratches.
The lens cap is a snap-on type that is emblazoned with the Sony Alpha logo. In addition, this version features prominently the "G" logo at its center, to match the high-end line of Sony SLR lenses that follow the G-type optical design.