The WR Protector protects the lens surface from dirt and dust as well as scratches. It comes comes standard with Sigma’s WR coating that repels water drops and provides resistance to fingerprints. Completely colorless so it does not affect color reproduction.When pitted against the standard coating offered by other brands, the benefits of Sigmas ultra-low reflection multicoated optics are crystal clear.Digital camera CCD or CMOS sensors are highly reflective objects and therefore susceptible to reflections. These reflections could spoil your photographs. Sigma Professional Filters have an ultra-low reflection multi-coating that dramatically reduces potential of sensor reflections and flare.