This is a dedicated 19° interchangeable lens for the Nanlite PJ-BM Projection Attachment (which is sold separately). This lens provides a tighter beam and greatly increases the brightness of the attached light. While the additional output is a huge bonus, the biggest benefits are the endless creative possibilities it provides. The Ultimate Light Shaping Tool Lighting a shoot is incredibly creative to begin with, but when you add the PJ-BM projector mount and this lens, the potential is unmatched. Create eye-catching textured backgrounds, razor-sharp spot effects, and anything else you can dream up. Dramatically Increases Light Output The 19° lens provides a substanially brighter output than the light only. It's far brighter than a light with a reflector, and often twice as bright as a light with a fresnel lens. Durable Aluminum Construction This lens and the compatible projection attachment (sold separately) feature a durable aluminum construction that stands up to the rigors of production work. Swapping Lenses is Easy Removing the current projection lens and swapping it for another is accomplished by removing a single screw. It only takes a few seconds and doesn't require any tools.