The Dorr 55mm Macro Filter Kit includes the 1+, 2+ and 4+ dioptre close up filters. The close-up is screwed into the filter thread of your camera lens and allows you to get your shot closer to the subject. They make great shots for nature photography. The longer the focal length you use, the more effective the close-up lens. The maximum achievable with a standard 50mm focal length is approximately 1:2.5. A metal protective case is included to keep your filters in top condition.