Most white balance tools require carrying around specialized items such as a White balance filter or a reference card but with the baLens Cap the lens cap on your camera is your white balance tool. The baLens White Balance Lens Cap comes with interchangeable neutral and warm domes and uses a center pinch-release mechanism to keep the cap locked firmly on your lens. Accurate white balance setting is as easy as putting the cap back on the camera point the camera at the light source and then snap a reference image for the use as your cameras pre-set white balance reference. So no matter how challenging the lighting situation you'll quickly and easily get beautiful balanced images without the need for bulky reference cards or lots of time on the computer after shooting.