The JTL 2104 4-Pc Trapezoid Clip-on Barn Door narrows the beam spread of a light source. They enable a photographer to aim light more accurately and reduce intensity in specific areas. The more leaves a barn door set has, or the longer the leaves the more precisely the beam can be controlled. They help create a 3-dimensional look to a lighting scheme by placing light in a specific area, or by keeping it away. The JTL Clip-On Barn Doors provide maximum versatility; they are compatible with any reflector dish on the market.