The 58mm White Balance Cap with 49mm and 52mm Ring Adapters from Vivitar allows you to easily calibrate your camera for color. Simply place the white balance cap over the lens and scene-specific light, combined with reflected light, is evaluated for accurate white balance. The 58mm comes with two adapter rings to use on 49mm and 52mm lenses. It is easily portable, convenient and weather resistant. An attached cord allows the cap to hang from the lens.