The Nanlite FL-20G Fresnel Lens is a glass Fresnel lens with an adjustable-length housing that focuses light output of the Nanlite Forza 300 and Forza 500. Dial-In The Beam Angle The Fl-20G's rotating barrel design enables beam angle adjustment from spot (10°) to flood (45°) with an intuitive twisting motion. Increase Brightness When set to a 10° spot the FL-20G can increase light output of the Forza 300 to 128679 Lux at 1 meter and the Forza 500 to a staggering 217649 Lux at 1 meter. Thermal Management The FL-20G's material design was specifically created to handle the heat output of the Forza 500 running at full brightness without any adverse effects. This makes it capable of managing the Forza 300's full output as well. Includes Barndoors The included metal barn doors enable further adjustment of the light output and control of spill. Quick Change Modifier Mount To keep up with the speed of production Nanlite kept the Forza 300 and 500's modifier mount fast and simple. With one push of a button and a quarter turn, you can swap out the FL-20G for any light modifier using a Bowens Style mount, including but not limited to Nanlite's own line of light modifiers. .