The 40.5mm Front Lens Cap by Pentax is designed to fit the Pentax 01 Standard Prime and the Pentax 02 Standard Zoom Lenses for the Q-series Interchangeable Lens cameras. This is a dedicated Pentax brand lens cap suitable for 40.5mm filter threads. It is a squeeze type lens cap that clicks in place, essential to keep your lenses free of dust, moisture, and smudges and to protect them from accidental impacts and scratches.