This is description on how the light is spread out as it leaves the light source. There are four different aspects of lights, left, right, front and back. Different light distribution will have different light intensity toward different direction. Symmetrical light distribution means that all four are the same. Asymmetrical light distribution means the application of lens has cause the light to shine in different direction. It is very important to choose the correct light distribution. As this will greatly affect the uniformity, potential light pollution, glare, lux/fc level and overall light efficiency of project. For example, for a warehouse with high shelf, using a sysmmetrical beam, will result in a lot of light on the top of the shelf only, if we use Singbee Rack B lens, this will create an eclipse light distribution so the light will only travel between the shelves. Greatly increase the use of lumen. Therefore with the same lamp, we will have higher project efficiency.