The Tiffen 4.5″ Round SR (self rotating) low-light linear polarizer was developed for shooting indoors in low-light conditions and for situations that do not provide enough light for a standard polarizer to be used.The low-light polarizer is purposely designed with a one-stop compensation factor and sets the stage for camera professionals to feel confident when stacking it with a Pro-Mist, Soft/FX, or other favorite diffusion filter.