The Sigma 105mm Protector Filter is a simple, clear filter with a 1x filter factor and is designed to provide general protection for your lens. This optically clear filter does not affect overall image quality while helping to prevent dust, scratches, moisture, and other elements from reaching or damaging your lens. This filter is multi-coated which helps to eliminate internal ghosting and reflections.Sigma Protector filters are constructed from optical glass with a black rim. Set within an aluminum-alloy filter ring that is durable while remaining lightweight, the glass provides increased clarity as well as color fidelity while the black rim further ensures that reflections do not occur along the filter's edge