Tronixpro 77mm Pro Series Hard Tulip Lens Hood For Sigma 17-50mm f/2.8 EX DC OS HSM Zoom Lens, Sigma 85mm f/1.4 EX DG HSM Lens, Sigma 120-400mm f/4.5-5.6 DG APO OS HSM Autofocus Lens This lens hood prevents image-degrading lens flare by blocking stray light from striking the surface of the lens It protects lenses from expensive front element damage Protects the front barrel from the inevitable impacts against walls, door frames, and other real-life obstacles. Microfiber Cloth 77mm Tulip Lens Hood