This LEE Filters SW150 Lightshield is designed to provide a LEE Filters SW150 Filter Holder with the same light-blocking functionality featured by a LEE Filters SW150 Mark II Filter Holder which has an integrated Lightshield. The SW150 Lightshield allows an SW150 Filter Holder, which does not have an integrated Lightshield, to more effectively use the LEE Filters SW150 Big Stopper and SW150 Little Stopper Filters.

Those filters each feature a built-in gasket that works with a compatible LEE Filters SW150-series filter holder with an integrated or add-on Lightshield to help form a seal that is intended to prevent stray light, which could have unwanted effects on exposure, from coming in between the filter and the lens behind it.

The LEE Filters SW150 Lightshield installs onto a LEE Filters SW150 Filter Holder by snapping into its pair of accessory slots located behind its one pair of filter slots. It is constructed from rubber for durability.