PolarPro BaseCamp Stage 3 Adapter The BaseCamp Stage 3 Adapter is placed on the Matte Box to allow the rectangular grey gradient filters to be placed on the filter holder. The BaseCamp ND4-GR and ND8-GR are perfect filters to balance the exposure of the sky and the ground. The soft gradient of a grayscale filter allows you to correct exposure smoothly and evenly. To correctly align the transition of the filter with the horizon of the landscape you need the Stage 3 Adapter. Information about the BaseCamp Matte Box The PolarPro BaseCamp Matte Box is a beautifully finished filter holder with flag that you can expand with all kinds of professional filters and accessories. There are regular Vario ND and ND filters available, or you can use the special Mist of Blue and GoldMorphic filters. Also different rails are available to mount the filter holder on. The PolarPro BaseCamp filter holder is specially designed for filming or photographing landscapes but can of course also be used in other situations.