the lens is there to help when using an inline exhaust system... it cuts the heat down substantially because it crates a vaccum within the reflector that pulls the heat away.. less heat = closer to plants = better plants/larger yields... if your trying to be cheap there are reflectors out there for 30 bucks a pop.. if you want to maximize your lights and can afford the sunleaves reflector and exhaust fans and the works its the way to go.. they are awesome...