A perfect Canon EW-73B replacement. Compatible with Canon 18-135mm EF-S f/3.5-5.6 IS, 17-85mm EF-S f/4.5-5.6 IS USM Lenses. Altura Photo lens hood shades the end of the lens preventing unwanted light and flares, those cirlcles of light that appear in your pictures when a strong light source is just outside the frame. Handy reversible design allows you to attach the hood in reverse for easy storage in your bag. Made of high impact plastic for an extremely solid and lightweight feel.