The 2-way Nanlite Fabric Barndoors and Grid for PavoTube 15C measures approximately 60cm in length, is made of lightweight ripstop nylon, and attachs to the LED tube and allow you to narrow and shape the wide 180-degree beam spread of the tube to as narrow as 5 degrees to light specific areas of the subject. Alternately, you can use the included fabric grid to narrow the beam spread to 45 degrees, while the barndoors eliminate spill light.